Create, Edit, or Compose Bitmap Images With These Command-line Options
Below is list of command-line options recognized by the ImageMagick
Adaptively blur pixels, with decreasing effect near edges. |
A Gaussian operator of the given radius and standard deviation (sigma) is used. If sigma is not given it defaults to 1.
Resize the image using data-dependent triangulation. |
See Image Geometry for complete details about the geometry argument. The -adaptive-resize option defaults to data-dependent triangulation. Use the -filter to choose a different resampling algorithm. Offsets, if present in the geometry string, are ignored, and the -gravity option has no effect.
Adaptively sharpen pixels, with increasing effect near edges. |
A Gaussian operator of the given radius and standard deviation (sigma) is used. If sigma is not given it defaults to 1.
Join images into a single multi-image file. |
This option is enabled by default. An attempt is made to save all images ofan image sequence into the given output file. However, some formats, such asJPEG and PNG, do not support more than one image per file, and in that caseImageMagick is forced to write each image as a separate file. As such, ifmore than one image needs to be written, the filename given is modified byadding a -scene number before the suffix, in order tomake distinct names for each image.
Use +adjoin to force each image to be written toseparate files, whether or not the file format allows multiple images per file(for example, GIF, MIFF, and TIFF).
Including a C-style integer format string in the output filename willautomagically enable +adjoin and are used to specifywhere the -scene number is placed in the filenames. Thesestrings, such as '%d' or '%03d', are familiar to thosewho have used the standard printf()' C-library function. As anexample, the command
$ convert logo: rose: -morph 15 my%02dmorph.jpg
will create a sequence of 17 images (the two given plus 15 more created by-morph), named: my00morph.jpg, my01morph.jpg,my02morph.jpg, ..., my16morph.jpg.
In summary, ImageMagick tries to write all images to one file, but willsave to multiple files, if any of the following conditions exist...
- the output image's file format does not allow multi-image files,
- the +adjoin option is given, or
- a printf() integer format string (eg: "%d") is present in the output filename.
Set the drawing transformation matrix for combined rotating and scaling. |
This option sets a transformation matrix, for use by subsequent
The matrix entries are entered as comma-separated numeric values either inquotes or without spaces.
Internally, the transformation matrix has 3x3 elements, but three of themare omitted from the input because they are constant. The new (transformed)coordinates (x', y') of a pixel atposition (x, y) in the originalimage are calculated using the following matrix equation.

The size of the resulting image is that of the smallest rectangle thatcontains the transformed source image. The parameters
The transformation matrix complies with the left-handed pixel coordinatesystem: positive x and y directionsare rightward and downward, resp.; positive rotation is clockwise.
If the translation coefficients tx and
Scaling by the factors sx and
See -transform, and the
-affine sx,0,0,sy
Translation by a displacement (tx, ty) is accomplished like so:
-affine 1,0,0,1,tx,ty
Rotate clockwise about the origin (the upper left-hand corner) by an angle a by lettingc = cos(a), s = sin(a), and using the following.
-affine c,s,-s,c
The cumulative effect of a sequence of -affine transformations can be accomplished by instead by a single -affine operation using the matrix equal to the product of the matrices of the individual transformations.
An attempt is made to detect near-singular transformation matrices. If the matrix determinant has a sufficiently small absolute value it is rejected.
Gives control of the alpha/matte channel of an image. |
Used to set a flag on an image indicating whether or not to use existing alphachannel data, to create an alpha channel, or to perform other operations on the alpha channel. Choose the argument type from the list below.
type | Description |
---|---|
Activate or On | Enable the image's transparency channel. Note normally Set should be used instead of this, unless you specifically need to preserve existing (but specifically turned Off) transparency channel. |
Deactivate or Off | Disables the image's transparency channel. Does not delete or change the existing data, just turns off the use of that data. |
Set | Activates the alpha/matte channel. If it was previously turned off then it also resets the channel to opaque. If the image already had the alpha channel turned on, it will have no effect. |
Opaque | Enables the alpha/matte channel and forces it to be fully opaque. |
Transparent | Activates the alpha/matte channel and forces it to be fully transparent. This effectively creates a fully transparent image the same size as the original and with all its original RGB data still intact, but fully transparent. |
Extract | Copies the alpha channel values into all the color channels and turns 'Off' the the image's transparency, so as to generate a gray-scale mask of the image's shape. The alpha channel data is left intact just deactivated. This is the inverse of 'Copy'. |
Copy | Turns 'On' the alpha/matte channel, then copies the gray-scale intensity of the image, into the alpha channel, converting a gray-scale mask into a transparent shaped mask ready to be colored appropriately. The color channels are not modified. |
Shape | As per 'Copy' but also colors the resulting shape mask with the current background color. That is the RGB color channels is replaced, with appropriate alpha shape. |
Background | Set any fully-transparent pixel to the background color, while leaving it fully-transparent. This can make some image file formats, such as PNG, smaller as the RGB values of transparent pixels are more uniform, and thus can compress better. |
Flatten | Composite the image over the background color. |
Note that while the +matte operation is the same as"-alpha Off", the -matte operation is the same as "-alphaSet" and not "-alpha On".
-annotate degrees text
-annotate XdegreesxYdegrees text
-annotate XdegreesxYdegrees {+-}tx{+-}ty text
Annotate an image with text. |
This is a convenience for annotating an image with text. For more precise control over text annotations, use -draw.
The values Xdegrees and Ydegrees control the shears with respect to the , respectively, applied to the text, while tx and ty are offsets that give the location of the text relative to the upper left corner of the image.
Using -annotate degrees or -annotate degreesxdegrees produces an unsheared rotation of the text. The direction of the rotation is positive, which means a clockwise rotation if degrees is positive. (This conforms to the usual mathematical convention once it is realized that the positive y–direction is conventionally considered to be downward for images.)
The new (transformed) coordinates (x', y') of a pixel at position (x, y) in the image are calculated using the following matrix equation.

If tx and ty are omitted, they default to 0. This makes the bottom-left of the text becomes the upper-left corner of the image, which is probably undesirable. Adding a -gravity option in this case leads to nice results.
Text is any UTF-8 encoded character sequence. If text is of the form '@mytext.txt', the text is read from the file mytext.txt. Text in a file is taken literally; no embedded formatting characters are recognized.
Enable/Disable of the rendering of anti-aliasing pixels whendrawing fonts and lines. |
By default, objects (e.g. text, lines, polygons, etc.) are antialiased whendrawn. Use +antialias to disable the addition ofantialiasing edge pixels. This will then reduce the number of colors added toan image to just the colors being directly drawn. That is, no mixed colorsare added when drawing such objects.
Join current images vertically or horizontally. |
This option creates a single longer image image, by joining all the currentimages in sequence top-to-bottom. Use +append tostack images left-to-right.
If they are not of the same width, narrower images are padded with thecurrent -background color setting, and theirposition relative to each other can be controlled by the current
Lessen (or intensify) when adding noise to an image. |
Decrypt a PDF with a password. |
Use this option to supply a password for decrypting a PDF that has been encrypted using Microsoft Crypto API (MSC API). The encrypting using the MSC API is not supported.
For a different encryption method, see -encipher and -decipher.
Automagically adjust gamma level of image. |
This calculates the mean values of an image, then applies a calculated
This means that any solid 'gray' image becomes 50% gray.
This works well for real-life images with little or no extreme dark andlight areas, but tend to fail for images with large amounts of bright sky ordark shadows. It also does not work well for diagrams or cartoon like images.
It uses the -channel setting, (including the'sync' flag for channel synchronization), to determine which colorvalues is used and modified. As the default -channel setting is 'RGB,sync', channels are modifiedtogether by the same gamma value, preserving colors.
Automagically adjust color levels of image. |
This is a 'perfect' image normalization operator. It finds the exactminimum and maximum color values in the image and then applies a
The operator is not typically used for real-life images, image scans, orJPEG format images, as a single 'out-rider' pixel can set a bad min/max valuesfor the -level operation. On the other hand it is theright operator to use for color stretching gradient images being used togenerate Color lookup tables, distortion maps, or other 'mathematically'defined images.
The operator is very similar to the -normalize,
It uses the -channel setting, (including thespecial 'sync' flag for channel synchronization), to determinewhich color values are used and modified. As the default
Automagically orient (rotate) an image created by a digital camera. |
This operator reads and resets the EXIF image profile setting 'Orientation'and then performs the appropriate 90 degree rotation on the image to orientthe image, for correct viewing.
This EXIF profile setting is usually set using a gravity sensor in digitalcamera, however photos taken directly downward or upward may not have anappropriate value. Also images that have been orientation 'corrected' withoutreseting this setting, may be 'corrected' again resulting in a incorrectresult. If the EXIF profile was previously stripped, the
Average a set of images. |
An error results if the images are not identically sized.
Display the image centered on a backdrop. | [animate, display] |
This backdrop covers the entire workstation screen and is useful for hiding other X window activity while viewing the image. The color of the backdrop is specified as the background color. The color is specified using the format described under the -fill option.
Set the background color. |
The color is specified using the format described under the -fill option. The default background color (if none is specified or found in the image) is white.
Measure performance. |
Repeat the entire command for the given number of iterations and report the user-time and elapsed time. For instance, consider the following command and its output. Modify the benchmark with the -duration to run the benchmark for a fixed number of seconds and -concurrent to run the benchmark in parallel (requires the OpenMP feature).
$ convert logo: -resize 1000% -bench 5 logo.pngPerformance[4]: 5i 0.875657ips 6.880u 0:05.710
In this example, 5 iterations were completed at 0.875657 iterations per second, using 4 threads and 6.88 seconds of the user's allotted time, for a total elapsed time of 5.71 seconds.
Add bias when convolving an image. |
This option shifts the output of ‑convolve so that positive and negative results are relative to the specified bias value.
This is important for non-HDRI compilations of ImageMagick when dealing with convolutions that contain negative as well as positive values. This is especially the case with convolutions involving high pass filters or edge detection. Without an output bias, the negative values are clipped at zero.
When using an ImageMagick with the HDRI compile-time setting, ‑bias is not needed, as ImageMagick is able to store/handle anynegative results without clipping to the color value range(0..QuantumRange).
See the discussion on HDRI implementations of ImageMagick on the pageHigh Dynamic-Range Images. For more about HDRI go the ImageMagick Usage pages or this Wikipedia entry.
Use black point compensation. |
Force to black all pixels below the threshold while leaving all pixels at or above the threshold unchanged. |
The threshold value can be given as a percentage or as an absolute integer value within [0, QuantumRange] corresponding to the desired ‑channel value. See ‑threshold for more details on thresholds and resulting values.
blend an image into another by the given absolute value or percent. | [composite] |
Blend will average the images together ('plus') according to thepercentages given and each pixels transparency. If only a single percentagevalue is given it sets the weight of the composite or 'source' image, whilethe background image is weighted by the exact opposite amount. That is a-blend 30% merges 30% of the 'source' image with 70% of the'destination' image. Thus it is equivalent to -blend 30x70%.
Set the blue chromaticity primary point. |
simulate a scene at nighttime in the moonlight. Start with a factor of 1.5 |
Reduce image noise and reduce detail levels. |
Convolve the image with a Gaussian or normal distribution using the givenSigma value. The formula is:

The Sigma value is the important argument, anddetermines the actual amount of blurring that will take place.
The Radius is only used to determine the size of thearray which will hold the calculated Gaussian distribution. It should be aninteger. If not given, or set to zero, IM will calculate the largest possibleradius that will provide meaningful results for the Gaussian distribution.
The larger the Radius the slower theoperation is. However too small a Radius, and severaliasing effects may result. As a guideline, Radiusshould be at least twice the Sigma value, though threetimes will produce a more accurate result.
This option differs from -gaussian-blur simplyby taking advantage of the separability properties of the distribution. Herewe apply a single-dimensional Gaussian matrix in the horizontal direction,then repeat the process in the vertical direction.
The -virtual-pixel setting will determine howpixels which are outside the image proper are blurred into the final result.
-blur Width[xHeight[+Angle]]
Variably blur and image according to the overlay mapping. | [composite] |
Each pixel in the overlaid region is replaced with an Elliptical WeightedAverage (EWA) of the source image, scaled according to the grayscalemapping.
The ellipse is weighted with sigma set to the given Width and Height. The Heightdefaults to the Width for a normal circular Gaussianweighting. The Angle will rotate the ellipse fromhorizontal clock-wise.
The -virtual-pixel setting will determine howpixels which are outside the image proper are blurred into the final result.
Surround the image with a border of color. |
Set the width and height using the size portion of thegeometry argument. See Image Geometry for complete details about the geometry argument. Offsets areignored.
Set the border color by preceding with the
The -border operation is affected by the current
See also the -frame option, which has morefunctionality.
Set the border color. |
The color is specified using the format described under the -fill option.
The default border color is #DFDFDF, this shade of gray.
Set the border width. | [animate, display] |
Adjust the brightness and/or contrast of the image. |
Brightness and Contrast values apply changes to the input image. They arenot absolute settings. A brightness or contrast value of zero means no change.The range of values is -100 to +100 on each. Positive values increase thebrightness or contrast and negative values decrease the brightness or contrast.To control only contrast, set the brightness=0. To control only brightness,set contrast=0 or just leave it off.
You may also use -channel to control which channels toapply the brightness and/or contrast change. The default is to apply the sametransformation to all channels.
Brightness and Contrast arguments are converted to offset and slope of alinear transform and appliedusing -function polynomial "slope,offset".
The slope varies from 0 at contrast=-100 to almost vertical atcontrast=+100. For brightness=0 and contrast=-100, the result are totallymidgray. For brightness=0 and contrast=+100, the result will approach butnot quite reach a threshold at midgray; that is the linear transformationis a very steep vertical line at mid gray.
Negative slopes, i.e. negating the image, are not possible with thisfunction. All achievable slopes are zero or positive.
The offset varies from -0.5 at brightness=-100 to 0 at brightness=0 to +0.5at brightness=+100. Thus, when contrast=0 and brightness=100, the result istotally white. Similarly, when contrast=0 and brightness=-100, the result istotally black.
As the range of values for the arguments are -100 to +100, adding the '%'symbol is no different than leaving it off.
(This option has been replaced by the -limit option.) |
Assign a caption to an image. |
This option sets the caption meta-data of an image read in after thisoption has been given. To modify a caption of images already in memory use"-set caption".
The caption can contain special format characters listed in the
If the first character of string is
Caption meta-data is not visible on the image itself. To do that use the-annotate or -draw optionsinstead.
For example,
-caption "%m:%f %wx%h" bird.miff
produces an image caption of MIFF:bird.miff 512x480 (assumingthat the image bird.miff has a width of 512 and a height of480.
color correct with a color decision list. |
Here is an example color correction collection:
<?xml version="1.0" encoding="UTF-8"?><ColorCorrectionCollection xmlns="urn:ASC:CDL:v1.2"> <ColorCorrection id="cc06668"> <SOPNode> <Slope> 0.9 1.2 0.5 </Slope> <Offset> 0.4 -0.5 0.6 </Offset> <Power> 1.0 0.8 1.5 </Power> </SOPNode> <SATNode> <Saturation> 0.85 </Saturation> </SATNode> </ColorCorrection></ColorCorrectionCollection>
Specify those image color channels to which subsequent operators are limited. |
Choose from: Red, Green, Blue,Alpha, Cyan, Magenta, Yellow,Black, Opacity, Index, RGB,RGBA, CMYK, or CMYKA.
The channels above can also be specified as a comma-separated list or can beabbreviated as a concatenation of the letters 'R', 'G','B', 'A', 'O', 'C','M', 'Y', 'K'.For example, to only select the Red and Blue channelsyou can either use
-channel Red,Blue
or you can use the short hand form
-channel RB
All the channels that are present in an image can be specified using thespecial channel type All. Not all operators are 'channel capable',but generally any operators that are generally 'grey-scale' image operators,will understand this setting. See individual operator documentation.
On top of the normal channel selection an extra flag can be specified,'Sync'. This is turned on by default and if set means thatoperators that understand this flag should perform: cross-channelsynchronization of the channels. If not specified, then most grey-scaleoperators will apply their image processing operations to each individualchannel (as specified by the rest of the -channelsetting) completely independently from each other.
For example for operators such as -auto-level and-auto-gamma the color channels are modifiedtogether in exactly the same way so that colors will remain in-sync. Withoutit being set, then each channel is modified separately andindependently, which may produce color distortion.
The -morphology 'Convolve' methodand the -compose mathematical methods, also understandsthe 'Sync' flag to modify the behaviour of pixel colors accordingto the alpha channel (if present). That is to say it will modify the imageprocessing with the understanding that fully-transparent colors should notcontribute to the final result.
Basically, by default, operators work with color channels in synchronous, andtreats transparency as special, unless the -channelsetting is modified so as to remove the effect of the 'Sync' flag.How each operator does this depends on that operators current implementation.Not all operators understands this flag at this time, but that is changing.
To print a complete list of channel types, use -listchannel.
By default, ImageMagick sets -channel to the value'RGBK,sync', which specifies that operators act on all colorchannels except the transparency channel, and that all the color channels areto be modified in exactly the same way, with an understanding of transparency(depending on the operation being applied). The 'plus' form
Options that are affected by the -channel settinginclude the following.-auto-gamma,-auto-level,-black-threshold,-blur,-clamp,-clut,-combine,-composite (Mathematical compose methods only),-convolve,-contrast-stretch,-evaluate,-function,-fx,-gaussian-blur,-hald-clut,-motion-blur,-morphology,-negate,-normalize,-ordered-dither,-radial-blur,-random-threshold,-separate,-threshold, and-white-threshold.
Warning, some operators behave differently when the +channel default setting is in effect, verses ANY user defined
For example -threshold will by default gray-scalethe image before thresholding, if no -channel settinghas been defined. This is not 'Sync flag controlled, yet.
Also some operators such as -blur,
As a alpha channel is optional within images, some operators will read thecolor channels of an image as a greyscale alpha mask, when the image has noalpha channel present, and the -channel setting tellsthe operator to apply the operation using alpha channels. The
Restrict image colors from 0 to the quantum depth. |
Simulate a charcoal drawing. |
Remove pixels from the interior of an image. |
See Image Geometry for complete details about the geometry argument. The widthand height given in the of the sizeportion of the geometry argument give the number ofcolumns and rows to remove. The offset portion ofthe geometry argument is influenced bya -gravity setting, if present.
The -chop option removes entire rows and columns,and moves the remaining corner blocks leftward and upward to close the gaps.
While it can remove internal rows and columns of pixels, it is moretypically used with as -gravity setting and zerooffsets so as to remove a single edge from an image. Compare this to
Using -chop effectively undoes the results of a
Apply the clipping path if one is present. |
If a clipping path is present, it is applied to subsequent operations.
For example, in the command
$ convert -clip -negate cockatoo.tif negated.tif
only the pixels within the clipping path are negated.
The -clip feature requires the XML library. If the XML library is not present, the option is ignored.
Clip the image as defined by this mask. |
Use the given image as a 'do-not-modify' mask of the current images in thecurrent image sequence. Assuming the clipmask is a greyscale image the samesize at the one already in memory, any areas that is white will not bemodified by any of the 'image processing operators' that follow, until themask is removed. Pixels in the black areas of the clip mask will be modifiedas normal.
In some ways this is similar to (though not the same) as defininga rectangular -region, or using the negative of themask (thrid) image in a three image -composite,operation.
Clip along a named path from the 8BIM profile. |
This is almost identical to -clip.
make a clone of an image (or images). |
Inside parenthesis (where the operator is normally used) it will make aclone of the images from the last 'pushed' image sequence, and adds them tothe end of the current image sequence. Outside parenthesis(not recommended) it clones the images from the current image sequence.
Specify the image by its index in the sequence. The first image is index0. Negative indexes are relative to the end of the sequence; forexample, −1represents the last image of the sequence. Specify a range of images with adash (e.g. 0−4). Separate multiple indexes with commas but nospaces (e.g. 0,2,5). A value of '0−−1 willeffectively clone all the images.
The +clone will simply make a copy of the last imagein the image sequence, and is thus equivalent to using a argument of'−1'.
Replace the channel values in the first image using eachcorresponding channel in the second image as a colorlookup table. |
The second (LUT) image is ordinarily a gradient image containing thehistogram mapping of how each channel should be modified. Typically it is aeither a single row or column image of replacement color values. If largerthan a single row or column, values are taken from a diagonal line fromtop-left to bottom-right corners.
The lookup is further controlled by the
This operator is especially suited to replacing a grayscale image with aspecific color gradient from the CLUT image.
Only the channel values defined by the -channelsetting will have their values replaced. In particular, since the default
If either the image being modified, or the lookup image, contains notransparency (i.e. -alpha is turned 'off') but the
See also -hald-clut which replaces colorsaccording to the lookup of the full color RGB value from a 2D representationof a 3D color cube.
Fully define the look of each frame of an GIF animation sequence, to form a 'film strip' animation. |
Overlay each image in an image sequence according toits -dispose meta-data, to reproduce the look ofan animation at each point in the animation sequence. All images should bethe same size, and are assigned appropriate GIF disposal settings for theanimation to continue working as expected as a GIF animation. Such framesare more easily viewed and processed than the highly optimized GIF overlayimages.
The animation can be re-optimized after processing usingthe -layers method 'optimize', althoughthere is no guarantee that the restored GIF animation optimization isbetter than the original.
Colorize the image by an amount specified by value using the color specified by the most recent -fill setting. |
Specify the amount of colorization as a percentage. Separate colorizationvalues can be applied to the red, green, and blue channels of the image witha comma-delimited list of colorizationvalues (e.g., -colorize 0,0,50).
Define the colormap type. | [animate, display] |
The type can be shared or private.
This option only applies when the default X server visualis PseudoColor or GrayScale. Referto -visual for more details. By default,a shared colormap is allocated. The image shares colors withother X clients. Some image colors could be approximated,therefore your image may look very different than intended.If private is chosen, the image colors appear exactlyas they are defined. However, other clients may go technicolorwhen the image colormap is installed.
Set the preferred number of colors in the image. |
The actual number of colors in the image may be less than your request,but never more. Note that this a color reduction option. Images with fewerunique colors than specified by value will have anyduplicate or unused colors removed. The ordering of an existing colorpalette may be altered. When converting an image from color to grayscale,it is more efficient to convert the image to the gray colorspace beforereducing the number of colors. Refer tothe color reduction algorithm for more details.
apply color correction to the image. |
This option permits saturation changes, hue rotation, luminance to alpha,and various other effects. Although variable-sized transformation matricescan be used, typically one uses a 5x5 matrix for an RGBA image and a 6x6for CMYKA (or RGBA with offsets). The matrix is similar to those used byAdobe Flash except offsets are in column 6 rather than 5 (in support ofCMYKA images) and offsets are normalized (divide Flash offset by 255).
As an example, to add contrast to an image with offsets, try this command:
convert kittens.jpg -color-matrix \ " 1.5 0.0 0.0 0.0, 0.0, -0.157 \ 0.0 1.5 0.0 0.0, 0.0, -0.157 \ 0.0 0.0 1.5 0.0, 0.0, -0.157 \ 0.0 0.0 0.0 1.0, 0.0, 0.0 \ 0.0 0.0 0.0 0.0, 1.0, 0.0 \ 0.0 0.0 0.0 0.0, 0.0, 1.0" kittens.png
Set the image colorspace. |
Choices are:
CMY CMYK Gray HSB HSL HWB Lab Log OHTA Rec601Luma Rec601YCbCr Rec709Luma Rec709YCbCr RGB sRGB Transparent XYZ YCbCr YCC YIQ YPbPr YUV
To print a complete list of colorspaces, use -list colorspace.
For a more accurate color conversion to or from the RGB, CMYK, or grayscale colorspaces, use the -profile option.
CMY |
---|
C=QuantumRange−R |
M=QuantumRange−G |
Y=QuantumRange−B |
CMYK — starts with CMY from above |
K=min(C,Y,M) |
C=QuantumRange*(C−K)/(QuantumRange−K) |
M=QuantumRange*(M−K)/(QuantumRange−K) |
Y=QuantumRange*(Y−K)/(QuantumRange−K) |
Gray |
Gray = 0.29900*R+0.58700*G+0.11400*B |
HSB — Hue, Saturation, Brightness; like a cone peak downward |
H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green |
S=distance from axis outward |
B=distance along axis from bottom upward; B=max(R,G,B); intensity-like |
HSL — Hue, Saturation, Lightness; like a double cone end-to-end with peaks at very top and bottom |
H=angle around perimeter (0 to 360 deg); H=0 is red; increasing angles toward green |
S=distance from axis outward |
L=distance along axis from bottom upward; L=0.5*max(R,G,B) + 0.5*min(R,G,B); intensity-like |
HWB — Hue, Whiteness, Blackness |
Hue (complicated equation) |
Whiteness (complicated equation) |
Blackness (complicated equation) |
LAB |
L (complicated equation relating X,Y,Z) |
A (complicated equation relating X,Y,Z) |
B (complicated equation relating X,Y,Z) |
LOG |
I1 (complicated equation involving logarithm of R) |
I2 (complicated equation involving logarithm of G) |
I3 (complicated equation involving logarithm of B) |
OHTA — approximates principal components transformation |
I1=0.33333*R+0.33334*G+0.33333*B; intensity-like |
I2=(0.50000*R+0.00000*G−0.50000*B)*(QuantumRange+1)/2 |
I3=(−0.25000*R+0.50000*G−0.25000*B)*(QuantumRange+1)/2 |
Rec601Luma |
Gray = 0.29900*R+0.58700*G+0.11400*B |
Rec601YCbCr |
Y=0.299000*R+0.587000*G+0.114000*B; intensity-like |
Cb=(−0.168736*R-0.331264*G+0.500000*B)*(QuantumRange+1)/2 |
Cr=(0.500000*R−0.418688*G−0.081312*B)*(QuantumRange+1)/2 |
Rec709Luma |
Gray=0.21260*R+0.71520*G+0.07220*B |
Rec709YCbCr |
Y=0.212600*R+0.715200*G+0.072200*B; intensity-like |
Cb=(−0.114572*R−0.385428*G+0.500000*B)*(QuantumRange+1)/2 |
Cr=(0.500000*R−0.454153*G−0.045847*B)*(QuantumRange+1)/2 |
sRGB |
if R ≤ .04045 then Rs=R/12.92 else Rs=((R+.055)/1.055)^2.4 |
if G ≤ .04045 then Gs=B/12.92 else Gs=((G+.055)/1.055)^2.4 |
if B ≤ .04045 then Bs=B/12.92 else Bs=((B+.055)/1.055)^2.4 |
XYZ |
X=0.4124240*R+0.3575790*G+0.1804640*B |
Y=0.2126560*R+0.7151580*G+0.0721856*B |
Z=0.0193324*R+0.1191930*G+0.9504440*B |
YCC |
Y=(0.29900*R+0.58700*G+0.11400*B) (with complicated scaling); intensity-like |
C1=(−0.29900*R−0.58700*G+0.88600*B) (with complicated scaling) |
C2=(0.70100*R−0.58700*G−0.11400*B) (with complicated scaling) |
YCbCr |
Y=0.299000*R+0.587000*G+0.114000*B; intensity-like |
Cb=(−0.168736*R−0.331264*G+0.500000*B)*(QuantumRange+1)/2 |
Cr=(0.500000*R−0.418688*G−0.081312*B)*(QuantumRange+1)/2 |
YIQ |
Y=0.29900*R+0.58700*G+0.11400*B; intensity-like |
I=(0.59600*R−0.27400*G−0.32200*B)*(QuantumRange+1)/2 |
Q=(0.21100*R−0.52300*G+0.31200*B)*(QuantumRange+1)/2 |
YPbPr |
Y=0.299000*R+0.587000*G+0.114000*B; intensity-like |
Pb=(−0.168736*R−0.331264*G+0.500000*B)*(QuantumRange+1)/2 |
Pr=(0.500000*R−0.418688*G−0.081312*B)*(QuantumRange+1)/2 |
YUV |
Y=0.29900*R+0.58700*G+0.11400*B; intensity-like |
U=(−0.14740*R−0.28950*G+0.43690*B)*(QuantumRange+1)/2 |
V=(0.61500*R−0.51500*G−0.10000*B)*(QuantumRange+1)/2 |
Combine one or more images into a single image. |
The channels (previously set by -channel) of the combined image are taken from the grayscale values of each image in the sequence, in order. For the default -channel setting of RGB, this means the first image is assigned to the Red channel, the second to the Green channel, the third to the Blue.
This option can be thought of as the inverse to -separate, so long as the channel settings are the same. Thus, in the following example, the final image should be a copy of the original.
$ convert original.png -channel RGB -separate sepimage.png $ convert sepimage-0.png sepimage-1.png sepimage-2.png -channel RGB \
-combine imagecopy.png
Embed a comment in an image. |
This option sets the comment meta-data of an image read in after thisoption has been given. To modify a comment of images already in memory use"-set comment".
The comment can contain special format characters listed in the
If the first character of string is
Comment meta-data are not visible on the image itself. To do that use the-annotate or -draw optionsinstead.
For example,
-comment "%m:%f %wx%h" bird.miff
produces an image comment of MIFF:bird.miff 512x480 (assumingthat the image bird.miff has a width of 512 and a height of480.
Set the type of image composition. |
See Alpha Compositing fora detailed discussion of alpha compositing.
This setting effects image processing operators that merge two (or more)images together in some way. This includes the operators,-composite,-layers composite,-flatten,-mosaic,-layers merge,-border,-frame,and -extent.
It is also one of the primary options for the "composite"command.
Perform alpha composition on two images and an optional mask |
Take the first image 'destination' and overlay the second 'source' imageaccording to the current -compose setting. The locationof the 'source' or 'overlay' image is controlled according to
If a third image is given this is treated as a gray-scale 'mask' imagerelative to the first 'destination' image. This mask will limit what parts ofthe destination can be modified by the image composition. However for the'displace' compose method, the mask is used to provide a separateY-displacement image instead.
If a -compose method requires extra numericalarguments or flags these can be provided by setting the
Some -compose methods can modify the 'destination'image outside the overlay area. You can disable this by setting the special
Use pixel compression specified by type when writing the image. |
Choices are: None, BZip, Fax, Group4, JPEG, JPEG2000, Lossless, LZW, RLE or Zip.
To print a complete list of compression types, use -list compress.
Specify +compress to store the binary image in an uncompressed format. The default is the compression type of the specified image file.
If LZW compression is specified but LZW compression has not been enabled, the image data is written in an uncompressed LZW format that can be read by LZW decoders. This may result in larger-than-expected GIF files.
Lossless refers to lossless JPEG, which is only available if theJPEG library has been patched to support it. Use of lossless JPEG is generallynot recommended.
When writing an ICO file, you may request that the images be encoded inPNG format, by specifying Zip compression.
When writing a JNG file, specify Zip compression to request thatthe alpha channel be encoded in PNG "IDAT" format, or JPEGto request that it be encoded in JPG "JDAA" format.
Use the -quality option to set the compression levelto be used by JPEG, PNG, MIFF, and MPEG encoders.Use the -sampling-factor option to set thesampling factor to be used by JPEG, MPEG, and YUV encoders for down-samplingthe chroma channels.
Enhance or reduce the image contrast. |
This option enhances the intensity differences between the lighter and darker elements of the image. Use -contrast to enhance the image or +contrast to reduce the image contrast.
For a more pronounced effect you can repeat the option:
$ convert rose: -contrast -contrast rose_c2.png
Increase the contrast in an image by stretching the range of intensity values. |
While performing the stretch, black-out at most
Prior to ImageMagick 6.4.7-0, -contrast-stretch will black-out at most black-point pixels and white-out at most total pixelsminus white-point pixels. Or, if percent is used, black-out at most
Note that -contrast-stretch 0 will modify the image such thatthe image's min and max values are stretched to 0 and QuantumRange, respectively, without any loss of data due to burn-out orclipping at either end. This is not the same as -normalize, which is equivalent to -contrast-stretch 0.15x0.05% (orprior to ImageMagick 6.4.7-0, -contrast-stretch 2%x99%).
Internally operator works by creating a histogram bin, and then uses thatbin to modify the image. As such some colors may be merged together when theyoriginally fell into the same 'bin'.
All the channels are normalized in concert by the came amount so as topreserve color integrity, when the default +channelsetting is in use. Specifying any other -channelsetting will normalize the RGB channels independently.
See also -auto-level for a 'perfect'normalization of mathematical images.
This operator is under review for re-development.
Convolve an image with a user-supplied convolution kernel. |
The kernel is a matrix specified asa comma-separated list of integers (with no spaces), ordered left-to right,starting with the top row. Presently, only odd-dimensioned kernels aresupported, and therefore the number of entries in the specified
Note that the ‑convolve operator supports the ‑bias setting. This option shifts the convolution so thatpositive and negative results are relative to a user-specified bias value.This is important for non-HDRI compilations of ImageMagick when dealing withconvolutions that contain negative as well as positive values. This isespecially the case with convolutions involving high pass filters or edgedetection. Without an output bias, the negative values is clipped at zero.
When using an ImageMagick with the HDRI compile-time setting, ‑bias is not needed, as ImageMagick is able to store/handle anynegative results without clipping to the color value range (0..QuantumRange).See the discussion on HDRI implementations of ImageMagick on the page
Cut out one or more rectangular regions of the image. |
See Image Geometry for complete details about the geometry argument.
The width and height of the geometry argument give the size of the image that remains after cropping, and x and y in the offset (if present) gives the location of the top left corner of the cropped image with respect to the original image. To specify the amount to be removed, use -shave instead.
If the x and y offsets are present, a single image is generated, consisting of the pixels from the cropping region. The offsets specify the location of the upper left corner of the cropping region measured downward and rightward with respect to the upper left corner of the image. If the -gravity option is present with NorthEast, East, or SouthEast gravity, it gives the distance leftward from the right edge of the image to the right edge of the cropping region. Similarly, if the -gravity option is present with SouthWest, South, or SouthEast gravity, the distance is measured upward between the bottom edges.
If the x and y offsets are omitted, a set of tiles of the specified geometry, covering the entire input image, is generated. The rightmost tiles and the bottom tiles are smaller if the specified geometry extends beyond the dimensions of the input image.
By adding a exclamation character flag to the geometry argument, thecropped images virtual canvas page size and offset is set as if thegeometry argument was a viewport or window. This means the canvas page sizeis set to exactly the same size you specified, the image offset setrelative top left corner of the region cropped.
If the cropped image 'missed' the actual image on its virtual canvas, aspecial single pixel transparent 'missed' image is returned, and a 'cropmissed' warning given.
It might be necessary to +repage the image prior tocropping the image to ensure the crop coordinate frame is relocated to theupper-left corner of the visible image. This is especially true when you aregoing to write to an image format such as PNG that supports an imageoffset.
displace image colormap by amount. |
Amount defines the number of positions eachcolormap entry is shifted.
enable debug printout. |
The events parameter specifies which events are to be logged. It can be either None, All, Trace, or a comma-separated list consisting of one or more of the following domains: Accelerate, Annotate, Blob, Cache, Coder, Configure, Deprecate, Exception, Locale, Render, Resource, Security, TemporaryFile, Transform, X11, or User.
For example, to log cache and blob events, use.
$ convert -debug "Cache,Blob" rose: rose.png
The User domain is normally empty, but developers can log user events in their private copy of ImageMagick.
To print the complete list of debug methods, use -list debug.
Use the -log option to specify the format for debugging output.
Use +debug to turn off all logging.
Debugging may also be set using the MAGICK_DEBUG environment variable. The allowed values for the MAGICK_DEBUG environment variable are the same as for the -debug option.
Decipher and restore pixels that were previously transformed by -encipher. |
Get the passphrase from the file specified by filename.
For more information, see the webpage, ImageMagick: Encipher or Decipher an Image.
find areas that has changed between images |
Given a sequence of images all the same size, such as produced by -coalesce, replace the second and later images, with a smaller image of just the area that changed relative to the previous image.
The resulting sequence of images can be used to optimize an animation sequence, though will not work correctly for GIF animations when parts of the animation can go from opaque to transparent.
This option is actually equivalent to the -layers method 'compare-any'.
add specific global settings generally used to controlcoders and image processing operations. |
This option creates one or more definitions for coders and decoders to usewhile reading and writing image data. Definitions are generally used tocontrol image file format coder modules, and image processing operations,beyond what is provided by normal means. Defined settings are listed in
If value is missing for a definition, an empty-valueddefinition of a flag is created with that name. This used to control on/offoptions. Use +define key to remove definitionspreviously created. Use +define "*" to remove allexisting definitions.
The same 'artifact' settings can also be defined using the
The option and key are case-independent (they areconverted to lowercase for use within the decoders) while the valueis case-dependent.
Such settings are global in scope, and effect all images and operations.
The following definitions are just some of the artifacts that areavailable:
- compose:args=arguments
- Sets certain compose argument values when using convert ... -compose ... -composite. See Image Composition
- distort:scale=value
- Sets the output scaling factor for use with -distort
- distort:viewport=WxH+X+Y
- Sets the viewport for use with -distort
- dcm:display-range=reset
- Set the display range to the minimum and maximum pixel values for the DCM image format.
- dot:layout-engine=value
- Set the specify the layout engine for the DOT image format (e.g. neato).
- jpeg:extent=value
- Restrict the maximum JPEG file size, for example -define jpeg:extent=400kb.
- jpeg:size=geometry
- Set the size hint of a JPEG image, for example, -define jpeg:size=128x128. It is most useful for increasing performance and reducing the memory requirements when reducing the size of a large JPEG image.
- jp2:rate=value
- Specify the compression factor to use while writing JPEG-2000 files. The compression factor is the reciprocal of the compression ratio. The valid range is 0.0 to 1.0, with 1.0 indicating lossless compression. If defined, this value overrides the -quality setting. A quality setting of 75 results in a rate value of 0.06641.
- mng:need-cacheoff
- turn playback caching off for streaming MNG.
- png:bit-depth=value
- png:color-type=value
- desired bit-depth and color-type for PNG output. You can force the PNG encoder to use a different bit-depth and color-type than it would have normally selected, but only if this does not cause any loss of image quality. Any attempt to reduce image quality is treated as an error and no PNG file is written. E.g., if you have a 1-bit black-and-white image, you can use these "defines" to cause it to be written as an 8-bit grayscale, indexed, or even a 64-bit RGBA. But if you have a 16-million color image, you cannot force it to be written as a grayscale or indexed PNG. If you wish to do this, you must use the appropriate -depth, -colors, or -type directives to reduce the image quality prior to using the PNG encoder. Note that in indexed PNG files, "bit-depth" refers to the number of bits per index, which can be 1, 2, 4, or 8. In such files, the color samples always have 8-bit depth.
- png:compression-filter=value
- valid values are 0 through 7. 0-4 are the corresponding PNG filters, 5 means adaptive filtering except for images with a colormap, 6 means adaptive filtering for all images, 7 means MNG "loco" compression.
- png:compression-level=value
- valid values are 0 through 9, with 0 providing the least but fastest compression and 9 usually providing the best and always the slowest.
- png:compression-strategy=value
- valid values are 0 through 4, meaning default, filtered, huffman_only, rle, and fixed ZLIB compression strategy. If you are using an old zlib that does not support Z_RLE (before 1.2.0) or Z_FIXED (before 1.2.2.2), values 3 and 4, respectively, will use the zlib default strategy instead.
- png:format=value
- valid values are png8, png24, and png32. This property can be useful for specifying the specific PNG format to be used, when the usual method of prepending the format name to the output filename is inconvenient, such as when writing a PNG-encoded ICO file.
- png:exclude-chunk=value
- png:include-chunk=value
- ancillary chunks to be excluded from or included in PNG output.
Thevalue can be the name of a PNG chunk-type such as bKGD, a comma-separated list of chunk-types, or the word all or the word none. There must be no spaces in the list. Although PNG chunk-names are case-dependent, you can use all lowercase names if you prefer.
The "include-chunk" and "exclude-chunk" lists only affect the behavior of the PNG encoder and have no effect on the PNG decoder.
As a special case, if the sRGB chunk is excluded and the gAMA chunk is included, the gAMA chunk will only be written if gamma is not 1/2.2, since most decoders assume sRGB and gamma=1/2.2 when no colorspace information is included in the PNG file. Because the list is processed from left to right, you can achieve this with a single define:
-define png:include-chunk=none,gAMA
As a special case, if the sRGB chunk is not excluded and the PNG encoder recognizes that the image contains the sRGB ICC profile, the PNG encoder will write the sRGB chunk instead of the entire 3144-byte ICC profile. To force the PNG encoder to write the sRGB profile as an iCCP chunk in the output PNG instead of the sRGB chunk, exclude the sRGB chunk.
The critical PNG chunks IHDR, PLTE, IDAT, and IEND cannot be excluded. Any such entries appearing in the list will be ignored.
If the ancillary PNG tRNS chunk is excluded and the image has transparency, the PNG colortype is forced to be 4 or 6 (GRAY_ALPHA or RGBA). If the image is not transparent, then the tRNS chunk isn't written anyhow, and there is no effect on the PNG colortype of the output image.
The -strip option does the equivalent of the following for PNG output:
-define png:include-chunk=none,trns,gama
The default behavior is to include all known PNG ancillary chunks plus ImageMagick's private vpAg ("virtual page") chunk, and to exclude all PNG chunks that are unknown to ImageMagick, regardless of their PNG "copy-safe" status as described in the PNG specification.
Any chunk names that are not known to ImageMagick are ignored if they appear in either the "include-chunk" or "exclude-chunk" list. The ancillary chunks currently known to ImageMagick are bKGD, cHRM, gAMA, iCCP, oFFs, pHYs, sRGB, tEXt, tRNS, vpAg, and zTXt.
You can also put date in the list to include or exclude the "Date:create" and "Date:modify" text chunks that ImageMagick normally inserts in the output PNG.
- png:preserve-colormap
- Use the existing image->colormap. Normally the PNG encoder will try to optimize the palette, eliminating unused entries and putting the transparent colors first. If this flag is set, that behavior is suppressed.
- ps:imagemask
- If the ps:imagemask flag is defined, the PS3 and EPS3 coders will create Postscript files that render bilevel images with the Postscript imagemask operator instead of the image operator.
- quantum:format=type
- Set the type to floating-point to specify a floating-point format for raw files (e.g. GRAY:) or for MIFF and TIFF images in HDRI mode to preserve negative values. If -depth 16 is included, the result is a single precision floating point format. If -depth 32 is included, the result is double precision floating point format.
- showkernel=1
- Outputs (to 'standard error') all the information about a generated -morphology kernel.
- tiff:quantum:polarity=min-is-black
tiff:quantum:polarity=min-is-white - Toggles the photometric interpretation
- tiff:rows-per-strip=value
- Sets the number of rows per strip
- tiff:tile-geometry=WxH
- Sets the tile size for pyramid tiffs. Requires the suffix PTIF: before the outputname
For example, to create a postscript file that will render only the blackpixels of a bilevel image, use:
$ convert bilevel.tif -define ps:imagemask eps3:stencil.ps
Set attributes of the image registry by prefixing the value withregistry:. For example, to set a temporary path to put work files,use:
-define registry:temporary-path=/data/tmp
display the next image after pausing. |
This option is useful for regulating the animation of image sequences ticks/ticks-per-second seconds must expire before the display of the next image. The default is no delay between each showing of the image sequence. The default ticks-per-second is 100.
Use > to change the image delay only if its current value exceeds the given delay. < changes the image delay only if current value is less than the given delay. For example, if you specify 30> and the image delay is 20, the image delay does not change. However, if the image delay is 40 or 50, the delay it is changed to 30. Enclose the given delay in quotation marks to prevent the < or > from being interpreted by your shell as a file redirection.
delete the image, specified by its index, from the image sequence. |
Specify the image by its index in the sequence. The first image is index 0. Negative indexes are relative to the end of the sequence, for example, -1 represents the last image of the sequence. Specify a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use +delete to delete the last image in the current image sequence.
Set the horizontal and vertical resolution of an image for rendering to devices. |
This option specifies the image resolution to store while encoding a raster image or the canvas resolution while rendering (reading) vector formats such as Postscript, PDF, WMF, and SVG into a raster image. Image resolution provides the unit of measure to apply when rendering to an output device or raster image. The default unit of measure is in dots per inch (DPI). The -units option may be used to select dots per centimeter instead.
The default resolution is 72 dots per inch, which is equivalent to one point per pixel (Macintosh and Postscript standard). Computer screens are normally 72 or 96 dots per inch, while printers typically support 150, 300, 600, or 1200 dots per inch. To determine the resolution of your display, use a ruler to measure the width of your screen in inches, and divide by the number of horizontal pixels (1024 on a 1024x768 display).
If the file format supports it, this option may be used to update the stored image resolution. Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile is not stripped from the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.
The -density option sets an attribute and does not alter the underlying raster image. It may be used to adjust the rendered size for desktop publishing purposes by adjusting the scale applied to the pixels. To resize the image so that it is the same size at a different resolution, use the -resample option.
depth of the image. |
This the number of bits in a color sample within a pixel. Use this option to specify the depth of raw images whose depth is unknown such as GRAY, RGB, or CMYK, or to change the depth of any image after it has been read.
obtain image by descending window hierarchy. |
straighten an image. A threshold of 40% works for most images. |
Use -set option:deskew:auto-crop width to auto crop the image. The set argument is the pixel width of the image background (e.g 40).
reduce the speckles within an image. |
render text right-to-left or left-to-right. |
shift image pixels as defined by a displacement map. | [composite] |
With this option, the 'overlay' image, and optionally the 'mask' image,is used as a displacement map, which is used to displace the lookup ofwhat part of the 'background' image is seen at each point of the overlaidarea. Much like the displacement map is a 'lens' that redirects light shiningthrough it so as to present a distorted view the original 'background' imagebehind it.
Any perfect grey areas of the displacement map produce a zerodisplacement of the image. Black areas produce the given maximum negativedisplacement of the lookup point, while white produce a maximum positivedisplacement of the lookup.
Note that it is the lookup of the 'background' that is displaced, not adisplacement of the image itself. As such an area of the displacement mapcontaining 'white' will have the lookup point 'shifted' by a positive amount,and thus generating a copy of the destination image to the right/downward fromthe correct position. That is the image will look like it may have been'shifted' in a negative left/upward direction. Understanding this is a veryimportant in understanding how displacement maps work.
The given arguments define the maximum amount of displacement in pixelsthat a particular map can produce. If the displacement scale is large enoughit is also possible to lookup parts of the 'background' image that lie welloutside the bounds of the displacement map itself. That is you could veryeasily copy a section of the original image from outside the overlay areainto the overlay area.
The '%' flag makes the displacement scale relative to the size of theoverlay image (100% = half width/height of image). Using '!' switchespercentage arguments to refer to the destination image size instead.these flags were added as of IM v6.5.3-5.
Normally a single grayscale displacement map is provided, which with thegiven scaling values will determine a single direction (vector) in whichdisplacements can occur (positively or negatively). However, if you alsospecify a third image which is normally used as a mask,the composite image is used for horizontal Xdisplacement, while the mask image is used for vertical Ydisplacement. This allows you to define completely different displacementvalues for the X and Y directions, and allowing you to lookup any point withinthe scale bounds. In other words each pixel can lookupany other nearby pixel, producing complex 2 dimensional displacements, ratherthan a simple 1 dimensional vector displacements.
Alternatively rather than supplying two separate images, as of IM v6.4.4-0,you can use the 'red' channel of the overlay image to specify the horizontalor X displacement, and the 'green' channel for the vertical or Y displacement.
As of IM v6.5.3-5 any alpha channel in the overlay image is used as amask the transparency of the destination image. However areas outside theoverlaid areas will not be effected.
Specifies the X server to contact. | [animate, display] |
This option is used with convert for obtaining image or font from this X server. See X(1).
define the GIF disposal image setting for images that are being created or read in. |
The layer disposal method defines the way each the displayed image is to bemodified after the current 'frame' of an animation has finished beingdisplayed (after its 'delay' period), but before the next frame on ananimation is to be overlaid onto the display.
Here are the valid methods:
Undefined 0 No disposal specified (equivalent to 'none'). None 1 Do not dispose, just overlay next frame image. Background 2 Clear the frame area with the background color. Previous 3 Clear to the image prior to this frames overlay.
You can also use the numbers given above, which is what the GIF formatuses internally to represent the above settings.
To print a complete list of dispose methods, use -list dispose.
Use +dispose, turn off the setting and preventresetting the layer disposal methods of images being read in.
Use -set 'dispose' method to set the imagedisposal method for images already in memory.
maximum RMSE for subimage match (default 0.2). | [compare] |
dissolve an image into another by the given percent. | [composite] |
The opacity of the composite image is multiplied by the given percent, thenit is composited 'over' the main image. If src_percentis greater than 100, start dissolving the main image so it becomestransparent at a value of '200'. If both percentagesare given, each image are dissolved to the percentages given.
Note that dissolve percentages do not add, two opaque images dissolved'50,50', produce a 75% transparency. For a 50% + 50% blending of the twoimages, you would need to use dissolve values of '50,100'.
distort an image, using the given method and its required arguments. |
The arguments is a single string containing a listof floating point numbers separated by commas or spaces. The number ofand meaning of the floating point values depends on the distortion
Choose from these distortion types:
Method | Description | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
ScaleRotateTranslate or SRT | Distort image by first scaling and rotating about a given 'center', before translating that 'center' to the new location, in that order. It is an alternative method of specifying a 'Affine' type of distortion, but without shearing effects. It also provides a good way of rotating and displacing a smaller image for tiling onto a larger background (IE 2-dimensional animations). The number of arguments determine the specific meaning of each argument for the scales, rotation, and translation operations.
| ||||||||||||||||
Affine | Distort the image linearly by moving a list of at least 3 or more sets of control points (as defined below). Ideally 3 sets or 12 floating point values are given allowing the image to be linearly scaled, rotated, sheared, and translated, according to those three points. See also the related 'AffineProjection' and 'SRT' distortions. More than 3 sets given control point pairs (12 numbers) is least squares fitted to best match a linear affine distortion. If only 2 control point pairs (8 numbers) are given a two point image translation rotation and scaling is performed, without any possible shearing, flipping or changes in aspect ratio to the resulting image. If only one control point pair is provides the image is only translated, (which may be a floating point non-integer translation). This distortion does not include any form of perspective distortion. | ||||||||||||||||
AffineProjection | Linearly distort an image using the given Affine Matrix of 6 pre-calculated coefficients forming a set of Affine Equations to map the source image to the destination image. sx, rx, ry, sy, tx, ty See -affine setting for more detail, and meanings of these coefficients. The distortions 'Affine' and 'SRT' provide alternative methods of defining this distortion, with ImageMagick doing the calculations needed to generate the required coefficients. You can see the internally generated coefficients, by using a -verbose setting with those other variants. | ||||||||||||||||
BilinearForward BilinearReverse | Bilinear Distortion, given a minimum of 4 sets of coordinate pairs, or 16 values (see below). Not that lines may not appear straight after distortion, though the distance between coordinates will remain consistent. The 'BilinearForward' is used to map rectangles to any quadrilateral, while the 'BilinearReverse' form maps any quadrilateral to a rectangle, while preserving the straight line edges in each case. Note that 'BilinearForward' can generate invalid pixels which will be colored using the -mattecolor color setting. Also if the quadrilateral becomes 'flipped' the image may disappear. There are future plans to produce a true Bilinear distortion that will attempt to map any quadrilateral to any other quadrilateral, while preserving edges (and edge distance ratios). | ||||||||||||||||
Perspective | Perspective distort the images, using a list of 4 or more sets of control points (as defined below). More that 4 sets (16 numbers) of control points provide least squares fitting for more accurate distortions (for the purposes of image registration and panorama effects). Less than 4 sets will fall back to a 'Affine' linear distortion. Perspective Distorted images ensures that straight lines remain straight, but the scale of the distorted image will vary. The horizon is anti-aliased, and the 'sky' color may be set using the -mattecolor setting. | ||||||||||||||||
PerspectiveProjection | Do a 'Perspective' distortion biased on a set of 8 pre-calculated coefficients. You can get these coefficients by looking at the -verbose output of a 'Perspective' distortion, or by calculating them yourself. If the last two perspective scaling coefficients are zero, the remaining 6 represents a transposed 'Affine Matrix'. | ||||||||||||||||
Arc | Arc the image (variation of polar mapping) over the angle given around a circle.
This a variation of a polar distortion designed to try to preserve the aspect ratio of the image rather than direct Cartesian to Polar conversion. | ||||||||||||||||
Polar | Like 'Arc' but do a complete Cartesian to Polar mapping of the image. that is the height of the input image is mapped to the radius limits, while the width is wrapped around between the angle limits. Arguments: Rmax,Rmin CenterX,CenterY, start,end_angle All arguments are optional. With Rmin defaulting to zero, the center to the center of the image, and the angles going from -180 (top) to +180 (top). If Rmax is given the special value of ' 0 ', the the distance from the center to the nearest edge is used for the radius of the output image, which will ensure the whole image is visible (though scaled smaller). However a special value of '-1 ' will use the distance from the center to the furthest corner, This may 'clip' the corners from the input rectangular image, but will generate the exact reverse of a 'DePolar' with the same arguments. If the plus form of distort (+distort) is used output image center will default to 0,0 of the virtual canvas, and the image size adjusted to ensure the whole input image is made visible in the output image on the virtual canvas. | ||||||||||||||||
DePolar | Uses the same arguments and meanings as a 'Polar' distortion but generates the reverse Polar to Cartesian distortion. The special Rmax setting of ' 0 ' may however clip the corners of the input image. However using the special Rmax setting of '-1 ' (maximum center to corner distance) will ensure the whole distorted image is preserved in the generated result, so that the same argument to 'Polar' will reverse the distortion re-producing the original. Note that as this distortion requires the area resampling of a circular arc, which can not be handled by the builtin EWA resampling function. As such the normal EWA filters are turned off. It is recommended some form of 'super-sampling' image processing technique be used to produce a high quality result. | ||||||||||||||||
Barrel | Given the four coefficients (A,B,C,D) as defined by Helmut Dersch, perform a barrel or pin-cushion distortion appropriate to correct radial lens distortions. That is in photographs, make straight lines straight again. Arguments: A B C [ D [ X , Y ] ] or Ax Bx Cx Dx Ay By Cy Dy [ X , Y ] So that it forms the function Rsrc = r * ( A*r3 + B*r2 + C*r + D ) Where X,Y is the optional center of the distortion (defaulting to the center of the image). The second form is typically used to distort images, rather than correct lens distortions. | ||||||||||||||||
BarrelInverse | This is very similar to 'Barrel' with the same set of arguments, and argument handling. However it uses the inverse of the radial polynomial, so that it forms the function Rsrc = r / ( A*r3 + B*r2 + C*r + D ) Note that this is not the reverse of the 'Barrel' distortion, just a different barrel-like radial distortion method. | ||||||||||||||||
Shepards | Distort the given list control points (any number) using an Inverse Squared Distance Interpolation Method (Shepards Method). The control points in effect do 'localized' displacement of the image around the given control point (preserving the look and the rotation of the area near the control points. For best results extra control points should be added to 'lock' the positions of the corners, edges and other unchanging parts of the image, to prevent their movement. The distortion has been likened to 'taffy pulling' using nails, or pins' stuck in a block of 'jelly' which is then moved to the new position, distorting the surface of the jelly. Internally it is equivalent to generating a displacement map (see -displace) for source image color look-up using the -sparse-color method of the same name. |
To print a complete list of distortion methods, use -listdistort.
Many of the above distortion methods such as 'Affine','Perspective', and 'Shepards' use a list control pointsdefining how these points in the given image should be distorted in thedestination image. Each set of four floating point values represent a sourceimage coordinate, followed immediately by the destination image coordinate.This produces a list of values such as...
where U,V on the source image is mapped to X,Y on thedestination image.
For example, to warp an image using 'perspective' distortion,needs a list of at least 4 sets of coordinates, or 16 numbers. Here is theperspective distortion of the built-in "rose:" image. Note how spaces wereused to group the 4 sets of coordinate pairs, to make it easier to read andunderstand.
$ convert rose: -virtual-pixel black \
-distort Perspective '0,0,0,0 0,45,0,45 69,0,60,10 69,45,60,35' \
rose_3d_rotated.gif
If more that the required number of coordinate pairs are given fora distortion, the distortion method is 'least squares' fitted to produce thebest result for all the coordinate pairs given. If less than the ideal numberof points are given, the distort will generally fall back to a simpler form ofdistortion that can handles the smaller number of coordinates (usually a linear'Affine' distortion).
By using more coordinates you can make use of image registration tool tofind matching coordinate pairs in overlapping images, so as to improve the'fit' of the distortion. Of course a bad coordinate pair can also make the'fit' worse. Caution is always advised.
Colors are acquired from the source image according to the
$ convert -size 90x90 pattern:checkerboard -normalize -virtual-pixel tile \
-distort perspective '0,0,5,45 89,0,45,46 0,89,0,89 89,89,89,89' \
checks_tiled.jpg
Note that a infinitely tiled perspective images involving the horizon canbe very slow to generate due to the use of the high quality 'area resampling'function (added ImageMagick v6.3.5-9). You can turn off 'area resampling'using a -filter setting of 'point'(recommended if you plan to use super-sampling instead).
If an image generates invalid pixels, such as the 'sky' in the last'perspective' distortion example, -distortwill use the current -mattecolor setting for thesepixels. If you do not what these pixels to be visible, set the color to matchthe rest of the ground.
The output image size will by default be the same as the input image. Thismeans that if the part of the distorted image falls outside the viewed area ofthe 'distorted space', those parts is clipped and lost. However if you usethe plus form of the operator (+distort) the operatorwill attempt (if possible) to show the whole of the distorted image, whileretaining a correct 'virtual canvas' offset, for image layering. This offsetmay need to be removed using +repage, to remove if itis unwanted.
You can alternatively specify a special "-setoption:distort:viewport {geometry_string}" setting which will specifythe size and the offset of the generated 'viewport' image of the distortedimage space.
Adding a "-set option:distort:scale{scale_factor}" will scale the output image (viewport or otherwise) bythat factor without changing the viewed contents of the distorted image. Thiscan be used either for 'super-sampling' the image for a higher quality result,or for panning and zooming around the image (with appropriate viewportchanges, or post-distort cropping and resizing).
Setting -verbose setting, will cause
Affine rotations and shears (such as 'SRT' distortion), tend toproduce a cleaner result that the equivalent -rotateand/or -shear operation, with more control of due to theabove settings. It is algorithmically slower however, though that may not bethe case in ImageMagick's implementation.
Apply a Riemersma or Floyd-Steinberg error diffusion dither to images when general color reduction is applied via an option, or automagically when saving to specific formats. This enabled by default. |
Dithering places two or more colors in neighboring pixels so that to the eye a closer approximation of the images original color is reproduced. This reduces the number of colors needed to reproduce the image but at the cost of a lower level pattern of colors. Error diffusion dithers can use any set of colors (generated or user defined) to an image.
Dithering is turned on by default, to turn it off use the plus form of thesetting, +dither. This will also also render PostScriptwithout text or graphic aliasing. Disabling dithering often (but not always)leads to faster process, a smaller number of colors, but more cartoon likeimage coloring. Generally resulting in 'color banding' effects in areas withcolor gradients.
The color reduction operators -colors,
Alternatively you can use -random-threshold to generate purely random dither. Or use -ordered-dither to apply threshold mapped dither patterns, using uniform color maps, rather than specific color maps.
Annotate an image with one or more graphic primitives. |
Use this option to annotate or decorate an image with one or more graphic primitives. The primitives include shapes, text, transformations, and pixel operations.
The shape primitives:
point x,y line x0,y0 x1,y1 rectangle x0,y0 x1,y1 roundRectangle x0,y0 x1,y1 wc,hc arc x0,y0 x1,y1 a0,a1 ellipse x0,y0 rx,ry a0,a1 circle x0,y0 x1,y1 polyline x0,y0 ... xn,yn polygon x0,y0 ... xn,yn bezier x0,y0 ... xn,yn path path specification image operator x0,y0 w,h filename
The text primitive:
text x0,y0 string
The text gravity primitive:
gravity NorthWest, North, NorthEast, West, Center, East, SouthWest, South, or SouthEast
The text gravity primitive only affects the placement of text and does not interact with the other primitives. It is equivalent to using the -gravity command-line option, except that it is limited in scope to the -draw option in which it appears.
The transformation primitives:
rotate degrees translate dx,dy scale sx,sy skewX degrees skewY degrees
The pixel operation primitives:
color x0,y0 method matte x0,y0 method
The shape primitives are drawn in the color specified by the preceding -fill setting. For unfilled shapes, use -fill none. You can optionally control the stroke (the "outline" of a shape) with the -stroke and -strokewidth settings.
A point primitive is specified by a single point in the pixel plane, that is, by an ordered pair of integer coordinates, x,y. (As it involves only a single pixel, a point primitive is not affected by -stroke or -strokewidth.)
A line primitive requires a start point and end point.
A rectangle primitive is specified by the pair of points at the upper left and lower right corners.
A roundRectangle primitive takes the same corner points as a rectangle followed by the width and height of the rounded corners to be removed.
The circle primitive makes a disk (filled) or circle (unfilled). Give the center and any point on the perimeter (boundary).
The arc primitive is used to inscribe an elliptical segment in to a given rectangle. An arc requires the two corners used for rectangle (see above) followed by the start and end angles of the arc of the segment segment (e.g. 130,30 200,100 45,90). The start and end points produced are then joined with a line segment and the resulting segment of an ellipse is filled.
Use ellipse to draw a partial (or whole) ellipse. Give the center point, the horizontal and vertical "radii" (the semi-axes of the ellipse) and start and end angles in degrees (e.g. 100,100 100,150 0,360).
The polyline and polygon primitives require three or more points to define their perimeters. A polyline is simply a polygon in which the final point is not stroked to the start point. When unfilled, this is a polygonal line. If the -stroke setting is none (the default), then a polyline is identical to a polygon.
A coordinate is a pair of integers separated by a space or optional comma.
As an example, to define a circle centered at 100,100 that extends to 150,150 use:
-draw 'circle 100,100 150,150'
The Bezier primitive creates a spline curve and requires three or points to define its shape. The first and last points are the knots and these points are attained by the curve, while any intermediate coordinates are control points. If two control points are specified, the line between each end knot and its sequentially respective control point determines the tangent direction of the curve at that end. If one control point is specified, the lines from the end knots to the one control point determines the tangent directions of the curve at each end. If more than two control points are specified, then the additional control points act in combination to determine the intermediate shape of the curve. In order todraw complex curves, it is highly recommended either to use the path primitive or to draw multiple four-point bezier segments with the start and end knots of each successive segment repeated. For example:
-draw 'bezier 20,50 45,100 45,0 70,50'
-draw 'bezier 70,50 95,100 95,0 120,50'
A path represents an outline of an object, defined in terms of moveto (set a new current point), lineto (draw a straight line), curveto (draw a Bezier curve), arc (elliptical or circular arc) and closepath (close the current shape by drawing a line to the last moveto) elements. Compound paths (i.e., a path with subpaths, each consisting of a single moveto followed by one or more line or curve operations) are possible to allow effects such as donut holes in objects. (See Paths.)
Use image to composite an image with another image. Follow the image keyword with the composite operator, image location, image size, and filename:
-draw 'image SrcOver 100,100 225,225 image.jpg'
You can use 0,0 for the image size, which means to use the actualdimensions found in the image header. Otherwise, it is scaled to the givendimensions. See Alpha Compositing fora detailed discussion of alpha composition methods that are available.The "special augmented compose operators" such as "dissolve" that requirearguments cannot be used at present with the -draw image option.
Use text to annotate an image with text. Follow the text coordinates with a string. If the string has embedded spaces, enclose it in single or double quotes.
For example, the following annotates the image with Works like magick! for an image titled bird.miff.
-draw "text 100,100 'Works like magick!' "
See the -annotate option for another convenient way to annotate an image with text.
The rotate primitive rotates subsequent shape primitives and text primitives about the origin of the main image. If the -region option precedes the -draw option, the origin for transformations is the upper left corner of the region.
The translate primitive translates subsequent shape and text primitives.
The scale primitive scales them.
The skewX and skewY primitives skew them with respect to the origin of the main image or the region.
The transformations modify the current affine matrix, which is initialized from the initial affine matrix defined by the -affine option. Transformations are cumulative within the -draw option. The initial affine matrix is not affected; that matrix is only changed by the appearance of another -affine option. If another -draw option appears, the current affine matrix is reinitialized from the initial affinematrix.
Use the color primitive to change the color of a pixel to the fill color (see -fill). Follow the pixel coordinate with a method:
point replace floodfill filltoborder reset
Consider the target pixel as that specified by your coordinate. The point method recolors the target pixel. The replace method recolors any pixel that matches the color of the target pixel. Floodfill recolors any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder recolors any neighbor pixel that is not the border color. Finally, reset recolors all pixels.
Use matte to the change the pixel matte value to transparent. Follow the pixel coordinate with a method (see the color primitive for a description of methods). The point method changes the matte value of the target pixel. The replace method changes the matte value of any pixel that matches the color of the target pixel. Floodfill changes the matte value of any pixel that matches the color of the target pixel and is a neighbor, whereas filltoborder changes the matte value of any neighbor pixel that is not the border color (-bordercolor). Finally reset changes the matte value of all pixels.
You can set the primitive color, font, and font bounding box color with -fill, -font, and -box respectively. Options are processed in command line order so be sure to use these options before the -draw option.
Strings that begin with a number must be quoted (e.g. use '1.png' rather than 1.png).
Drawing primitives conform to the Magick Vector Graphics format.
duplicate an image one or more times. |
Specify the count and the image to duplicate by its index in the sequence. The first image is index 0. Negative indexes are relative to the end of the sequence, for example, -1 represents the last image of the sequence. Specify a range of images with a dash (e.g. 0-4). Separate indexes with a comma (e.g. 0,2). Use +duplicate to duplicate the last image in the current image sequence.
detect edges within an image. |
emboss an image. |
Encipher pixels for later deciphering by -decipher. |
Get the passphrase from the file specified by filename.
For more information, see the webpage, ImageMagick: Encipher or Decipher an Image.
specify the text encoding. |
Choose from AdobeCustom, AdobeExpert, AdobeStandard, AppleRoman, BIG5, GB2312, Latin 2, None, SJIScode, Symbol, Unicode, Wansung.
Specify endianness (MSB or LSB) of the image. |
To print a complete list of endian types, use the -list endian option.
Use +endian to revert to unspecified endianness.
Apply a digital filter to enhance a noisy image. |
perform histogram equalization on the image channel-by-channel. |
To perform histogram equalization on all channels in concert, transform the image into some other color space, such as HSL, OHTA, YIQ or YUV, then equalize the appropriate intensity-like channel, then convert back to RGB.
For example using HSL, we have: ... -colorspace HSL -channel lightness -equalize -colorspace RGB ...
For YIQ, YUV and OHTA use the red channel. For example, OHTA is a principal components transformation that puts most of the information in the first channel. Here we have ... -colorspace OHTA -channel red -equalize -colorspace RGB ...
Alter channel pixels by evaluating an arithmetic, relational, or logical expression. |
(See the -function operator for some multi-parameter functions. See the -fx operator if more elaborate calculations are needed.)
The behaviors of each operator are summarized in the following list. For brevity, the numerical value of a "pixel" referred to below is the value of the corresponding channel of that pixel, while a "normalized pixel" is that number divided by the maximum (installation-dependent) value QuantumRange. (If normalized pixels are used, they are restored, following the other calculations, to the full range by multiplying by QuantumRange.)
operator | Summary (see further below for details) |
---|---|
Abs | Add value to pixels and return absolute value. |
Add | Add value to pixels. |
AddModulus | Add value to pixels modulo QuantumRange. |
And | Binary AND of pixels with value. |
Cos, Cosine | Apply cosine to pixels with frequency value with 50% bias added. |
Divide | Divide pixels by value. |
Exp | base-e exponential function |
Exponential | base-e exponential function |
LeftShift | Shift the pixel values left by value bits (i.e., multiply pixels by 2value). |
Log | Apply scaled logarithm to normalized pixels. |
Max | Clip pixels at lower bound value. |
Mean | Add the value and divide by 2. |
Median | Choose the median value from an image sequence. |
Min | Clip pixels at upper bound value. |
Multiply | Multiply pixels by value. |
Or | Binary OR of pixels with value. |
Pow | Raise normalized pixels to the power value. |
RightShift | Shift the pixel values right by value bits (i.e., divide pixels by 2value). |
Set | Set pixel equal to value. |
Sin, Sine | Apply sine to pixels with frequency value with 50% bias added. |
Subtract | Subtract value from pixels. |
Xor | Binary XOR of pixels with value. |
Gaussian-noise | |
Impulse-noise | |
Laplacian-noise | |
Multiplicative-noise | (These are equivalent to the corresponding -noise operators.) |
PoissonNoise | |
Uniform-noise | |
Threshold | Threshold pixels larger than value. |
ThresholdBlack | Threshold pixels to zero values equal to or below value. |
ThresholdWhite | Threshold pixels to maximum values above value. |
The specified functions are applied only to each previously set
To print a complete list of -evaluate operators, use-list evaluate.
The results of the Add, Subtract andMultiply methods can also be achieved using either the
AddModulus has been added as of ImageMagick 6.4.8-4 and provides addition modulo the QuantumRange. It is therefore equivalent to Add unless the resulting pixel value is outside the interval [0, QuantumRange].
Exp or Exponential has been added as of ImageMagick 6.6.5-1 and works on normalized pixel values. The value used with Exp should be negative so as to produce a decaying exponential function. Non-negative values will always produce results larger unity and thus outside the interval [0, QuantumRange]. The formula is expressed below.
If the input image is squared, for example, using
Log has been added as of ImageMagick 6.4.2-1 and works on normalized pixel values. This a scaled log function. The value used with Log provides a scaling factor that adjusts the curvature in the graph of the log function. The formula applied to a normalized value u is below.
Pow has been added as of ImageMagick 6.4.1-9, and works onnormalized pixel values. Note that Pow is related to the
Cosine and Sine was added as of IM v6.4.8-8 andconverts the image values into a value according to a (co)sine wave function.The synonyms Cos and Sin may also be used. The outputis biased 50% and normalized by 50% so as to fit in the respective color valuerange. The value scaling of the period of thefunction (its frequency), and thus determines the number of 'waves' that willbe generated over the input color range. For example, if the
See also the -function operator, which is amulti-value version of evaluate.
Alter channel pixels by evaluating an arithmetic, relational, or logical expression over a sequence of images. |
To print a complete list of -evaluate-sequence operators, use -list evaluate.
Set the image size and offset. |
If the image is enlarged, unfilled areas are set to the background color. To position the image, use offsets in the geometry specification or precede with a -gravity setting. To specify how to compose the image with the background, use -compose.
This command reduces or expands a JPEG image to fit on an 800x600display. If the aspect ratio of the input image isn't exactly 4:3, then theimage is centered on an 800x600 black canvas:
$ convert input.jpg -resize 800x600 -background black -compose Copy \
-gravity center -extent 800x600 -quality 92 output.jpg
See Image Geometry for complete details about the geometry argument.
Extract the specified area from image. |
This option is most useful for extracting a subregion of a very large raw image. Note that these two commands are equivalent:
$ convert -size 16000x16000 -depth 8 -extract 640x480+1280+960 \
image.rgb image.png $ convert -size 16000x16000 -depth 8 'image.rgb[640x480+1280+960]' \
image.rgb image.png
If you omit the offsets, as in
$ convert -size 16000x16000 -depth 8 -extract 640x480 \
image.rgb image.png
the image is resized to the specified dimensions instead,equivalent to:
$ convert -size 16000x16000 -depth 8 -resize 640x480 image.rgb image.png
See Image Geometry for complete details about the geometry argument.
Set a font family for text. |
This setting suggests a font family that ImageMagick should try to use for rendering text. If the family can be found it is used; if not, a default font (e.g., "Arial") or a family known to be similar is substituted (e.g., "Courier" might be used if "System" is requested but not found).
For other settings that affect fonts, see the options -font, -stretch, -style, and -weight.
display features for each channel in the image in each of four directions (horizontal, vertical, left and right diagonals) for the specified distance. |
implements the forward discrete Fourier transform (DFT). |
This option is new as of ImageMagick 6.5.4-3 (and now working for Windows users in ImageMagick 6.6.0-9). It transforms an image from the normal (spatial) domain to the frequency domain. In the frequency domain, an image is represented as a superposition of complex sinusoidal waves of varying amplitudes. The image x and y coordinates are the possible frequencies along the x and y directions, respectively, and the pixel intensity values are complex numbers that correspond to the sinusoidal wave amplitudes. See for example, Fourier Transform, Discrete Fourier Transform and Fast Fourier Transform.
A single image name is provided as output for this option. However, the output result will have two components. It is either a two-frame image or two separate images, depending upon whether the image format specified supports multi-frame images. The reason that we get a dual output result is because the frequency domain represents an image using complex numbers, which cannot be visualized directly. Therefore, the complex values are automagically separated into a two-component image representation. The first component is the magnitude of the complex number and the second is the phase of the complex number. See for example, Complex Numbers.
The magnitude and phase component images must be specified using image formats that do not limit the color or compress the image. Thus, MIFF, TIF, PFM, EXR and PNG are the recommended image formats to use. All of these formats, except PNG support multi-frame images. So for example,
$ convert image.png -fft fft_image.miff
generates a magnitude image as fft_image.miff[0] and a phase image as fft_image.miff[1]. Similarly,
$ convert image.png -fft fft_image.png
generates a magnitude image as fft_image-0.png and a phase image as fft_image-1.png. If you prefer this representation, then you can force any of the other formats to produce two output images by including +adjoin following -fft in the command line.
The input image can be any size, but if not square and even-dimensioned, it is padded automagically to the larger of the width or height of the input image and to an even number of pixels. The padding will occur at the bottom and/or right sides of the input image. The resulting output magnitude and phase images is square at this size. The kind of padding relies on the -virtual-pixel setting.
Both output components will have dynamic ranges that fit within [0, QuantumRange], so that HDRI need not be enabled. Phase values nominally range from 0 to 2*π, but is scaled to span the full dynamic range.(The first few releases had non-HDRI scaled but HDRI not scaled). The magnitude image is not scaled and thus generally will contain very small values. As such, the image normally will appear totally black. In order to view any detail, the magnitude image typically is enhanced with a log function into what is usually called the spectrum. A log function is used to enhance the darker values more in comparison to the lighter values. This can be done, for example, as follows:
$ convert fft_image.miff[0] -contrast-stretch 0 \
-evaluate log 1000 fft_image_spectrum.png
where either -contrast-stretch 0 or -auto-level is used to scale the image to full dynamic range, first. The argument to the -evaluate log typically is specified between 100 and 10,000, depending upon the amount of detail that one wants to bring out in the spectrum. Larger values produce more visible detail. Too much detail, however, may hide the important features.
The FFTW delegate library is required to use -fft.
Use +fft to produce two output images that are the real and imaginary components of the complex valued Fourier transform.
However, as the real and imaginary components can contain negative values, this requires that IM be configured with HDRI enabled. In this case, you must use either MIFF, TIF, PFM or MPC formats for the real and imaginary component results, since they are formats that preserve both negative and fractional values without clipping them or truncating the fractional part. With either MIFF or TIF, one should add -define quantum:format=32, to allow those image types to work properly in HDRI mode without clipping.
The real and imaginary component images resulting from +fft are also square, even dimensioned images due to the same padding that was discussed above for the magnitude and phase component images.
See the discussion on HDRI implementations of ImageMagick on the pageHigh Dynamic-Range Images. For more about HDRI go the ImageMagick Usage pages, Fred's Fourier Processing With ImageMagick page or this Wikipedia entry.
color to use when filling a graphic primitive. |
This option accepts a color name, a hex color, or a numerical RGB, RGBA, HSL, HSLA, CMYK, or CMYKA specification. See Color Names for a description of how to properly specify the color argument.
Enclose the color specification in quotation marks to prevent the "#" or the parentheses from being interpreted by your shell.
For example,
-fill blue
-fill "#ddddff"
-fill "rgb(255,255,255)"
See -draw for further details.
To print a complete list of color names, use the -list color option.
Use this type of filter when resizing ordistorting an image. |
Use this option to affect the resizing operation of an image duringoperations such as -resize and -distort. For example you can use a simple resize filter such as:
Point Hermite Cubic Box Gaussian Catrom Triangle Quadratic Mitchell
The Bessel and Sinc filter is also provided (as wellas a faster SincFast equivalent form). However these filters aregenerally useless on their own as they are infinite filters that are beingclipped to the filters support size. Their direct use is not recommendedexcept via expert settings (see below).
Instead these special filter functions are typically windowed by a windowingfunction that the -filter setting defines. That isusing these functions will define a 'Windowed' filter, appropriate to theoperator involved. Windowed filters include:
Lanczos Hamming Parzen Blackman Kaiser Welsh Hanning Bartlett Bohman
Also one special self-windowing filter is also providedLagrange, which will automagically re-adjust its function dependingon the current 'support' or 'lobes' expert settings (see below).
If you do not select a filter with this option, the filter defaults toMitchell for a colormapped image, a image with a matte channel, orif the image is enlarged. Otherwise the filter default toLanczos.
To print a complete list of resize filters, use the -listfilter option.
You can modify how the filter behaves as it scales your image through theuse of these expert settings (see also -define and
- -define filter:blur=factor
- Scale the X axis of the filter (and its window). Use > 1.0 for blurry or < 1.0 for sharp. This should only be used with Gaussian and Gaussian-like filters simple filters, or you may not get the expected results.
- -define filter:support=radius
- Set the filter support radius. Defines how large the filter should be and thus directly defines how slow the filtered resampling process is. All filters have a default 'prefered' support size. Some filters like Lagrange and windowed filters adjust themselves depending on this value. With simple filters this value either does nothing (but slow the resampling), or will clip the filter function in a detrimental way.
- -define filter:lobes=count
- Set the number of lobes to use for the Sinc/Bessel filter. This an alternative way of specifying the 'support' range of the filter, that is designed to be more suited to windowed filters, especially when used for image distorts.
- -define filter:b=b-spline_factor
- -define filter:c=keys_alpha_factor
- Redefine the values used for cubic filters such as Cubic, Catrom, Mitchel, and Hermite, as well as the Parzen Sinc windowing function. If only one of the values are defined, the other is set so as to generate a 'Keys' type cubic filter. Values meaning was defined by a research paper by Mitchell-Netravali.
- -define filter:filter=filter_function
- Use this function directly as the scaling filter. This will allow you to directly use a windowing filter such as Blackman, rather than as its normal usage as a windowing function for 'Sinc' or 'Bessel' functions. If defined, no windowing function is used, unless the following expert setting is also defined.
- -define filter:window=filter_function
- The IIR (infinite impulse response) filters Bessel and Sinc are windowed (brought down to zero over the defined support range) with the given filter. This allows you to specify a filter function that is not normally used as a windowing function, such as Box, (which effectively turns off the windowing function), to window a Sinc, or the function the previous setting defined.
- -define filter:verbose=1
- This causes IM to print information on the final internal filter selection to standard output. This includes a commented header on the filter settings being used, and data allowing the filter weights to be easily graphed.
- Note however that some filters are internally defined in terms of other filters. The Lanczos filter for example is defined in terms of a SincFast windowed SincFast filter, while Mitchell is defined as a Cubic filter with specific 'B' and 'C' settings.
For example, to get a 8 lobe Bessel windowed Bessel filter:
$ convert image.png -filter bessel \
-set filter:window=bessel -set filter:lobes=8 \
-resize 150% image.jpg
Or a raw un-windowed Sinc filter with 4 lobes:
$ convert image.png -set filter:filter=sinc -set filter:lobes=4 \
-resize 150% image.jpg
Note that the use of expert options (except for 'blur' with simple resizefilters, and 'verbose' for viewing the internal filter selection), areprovided for image processing experts who have studied and understood howresize filters work. Without this knowledge, and an understanding of thedefinition of the actual filters involved, using expert settings are morelikely to be detrimental to your image resizing.
This is a simple alias for the -layers method "flatten". |
create a mirror image. |
reflect the scanlines in the vertical direction. The image will be mirroredupside-down.
floodfill the image with color at the specified offset. |
Flood fill starts from the given 'seed point' which is not gravity effected.Any color that matches within -fuzz color distance of thegiven color argument, connected to that 'seed point'will be replaced with the current -fill color.
Note that if the pixel at the 'seed point' does not itself match the givencolor (according to -fuzz), then noaction will be taken.
This operator works more like the -opaque option, thana more general flood fill that reads the matching color directly at the 'seed point'. For this form of flood fill, look at -draw and its 'color floodfill' drawing method.
create a mirror image. |
Reflect the scanlines in the horizontal direction, just like the image ina vertical mirror.
set the font to use when annotating images with text, or creating labels. |
To print a complete list of fonts, use the -list font option (for versions prior to 6.3.6, use 'type' instead of 'font').
In addition to the fonts specified by the above pre-defined list, you canalso specify a font from a specific source. For example Arial.ttfis a TrueType font file, ps:helvetica is PostScript font, andx:fixed is X11 font.
For other settings that affect fonts, see the options -family, -stretch, -style, and -weight.
Define the foreground color. |
The color is specified using the format described under the -fill option.
The default foreground color is black.
the image format type. |
When used with the mogrify utility, this option converts any image to the image format you specify. For a list of image format types supported by ImageMagick, use -list format.
By default the file is written to its original name. However, if the filename extension matches a supported format, the extension is replaced with the image format type specified with -format. For example, if you specify tiff as the format type and the input image filename is image.gif, the output image filename becomes image.tiff.
output formatted image characteristics. | [identify] |
See Format and Print Image Properties for an explanation on how to specify the argument to this option.
Surround the image with a border or beveled frame. |
The color of the border is specified with the -mattecolor command line option.
See Image Geometry for complete details about the geometry argument. The size portion of the
The -frame option is affected by the current
The image composition is notaffected by the -gravity option.
include the X window frame in the imported image. | [import] |
Apply a function to channel values. |
This operator performs calculations based on the given arguments to modify each of the color values for each previously set -channel in the image. See -evaluate for details concerning how the results of the calculations are handled.
This is can be considered a multi-argument version of the -evaluate operator. (Added in ImageMagick 6.4.8−8.)
Here, parameters is a comma-separated list of numerical values. The number of values varies depending on which function is selected. Choose the function from:
Polynomial Sinusoid Arcsin Arctan
To print a complete list of -function operators, use -list function. Descriptions follow.
- Polynomial
The Polynomial function takes an arbitrary number of parameters, these being the coefficients of a polynomial, in decreasing order of degree. That is, entering
-function Polynomial an,an-1,...a1,a0will invoke a polynomial function given by
an un + an-1 un-1 + ··· a1 u + a0,where u is pixel's original normalized channel value.
The Polynomial function can be used in place of Set (the constant polynomial) and Add, Divide, Multiply, and Subtract (some linear polynomials) of the -evaluate operator. The -level operator also affects channels linearly. Some correspondences follow.
-evaluate Set value -function Polynomial value (Constant functions; set value×100% gray when channels are RGB.) -evaluate Add value -function Polynomial 1,value -evaluate Subtract value -function Polynomial 1,−value -evaluate Multiply value -function Polynomial value,0 +level black% x white% -function Polynomial A,B (Reduce contrast. Here, A=(white-black)/100 and B=black/100.) The Polynomial function gives great versatility, since polynomials can be used to fit any continuous curve to any degree of accuracy desired.
- Sinusoid
The Sinusoid function can be used to vary the channel values sinusoidally by setting frequency, phase shift, amplitude, and a bias. These values are given as one to four parameters, as follows,
-function Sinusoid freq,[phase,[amp,[bias]]]where phase is in degrees. (The domain [0,1] of the function corresponds to 0 through freq×360 degrees.) The result is that if a pixel's normalized channel value is originally u, its resulting normalized value is given by
amp * sin(2*π* (freq * u + phase / 360)) + biasFor example, the following generates a curve that starts and ends at 0.9 (when u=0 and 1, resp.), oscillating three times between .7−.2=.5 and .7+.2=.9.
-function Sinusoid 3,-90,.2,.7
The default values of amp and bias are both .5. The default for phase is 0.
The Sinusoid function generalizes Sin and Cos of the -evaluate operator by allowing varying amplitude, phase and bias. The correspondence is as follows.
-evaluate Sin freq -function Sinusoid freq,0 -evaluate Cos freq -function Sinusoid freq,90 - ArcSin
The ArcSin function generates the inverse curve of a Sinusoid,and can be used to generate cylindrical distortion and displacement maps.The curve can be adjusted relative to both the input values and output rangeof values.
-function ArcSin width,[center,[range,[bias]]]
with all values given in terms of normalized color values (0.0 for black,1.0 for white). Defaulting to values covering the full range from 0.0 to 1.0for bout input (width), and output (
width) values. ' 1.0,0.5,1.0,0.5
'range/π * asin( 2/width * ( u - center ) ) + bias
- ArcTan
The ArcTan function generates a curve that smooth crosses fromlimit values at infinities, though a center using the given slope value.All these values can be adjusted via the arguments.
-function ArcTan slope,[center,[range,[bias]]]
Defaulting to '
1.0,0.5,1.0,0.5
'.range/π * atan( slope*π * ( u - center ) ) + bias
Colors within this distance are considered equal. |
A number of algorithms search for a target color. By default the color must be exact. Use this option to match colors that are close to the target color in RGB space. For example, if you want to automagically trim the edges of an image with -trim but the image was scanned and the target background color may differ by a small amount. This option can account for these differences.
The distance can be in absolute intensity units or, by appending % as a percentage of the maximum possible intensity (255, 65535, or 4294967295).
apply a mathematical expression to an image or image channels. |
If the first character of expression is @, the expression is read from a file titled by the remaining characters in the string.
See FX, The Special Effects Image Operator for a detailed discussion of this option.
level of gamma correction. |
The same color image displayed on two different workstations may look different due to differences in the display monitor. Use gamma correction to adjust for this color difference. Reasonable values extend from 0.8 to 2.3. Gamma less than 1.0 darkens the image and gamma greater than 1.0 lightens it. Large adjustments to image gamma may result in the loss of some image information if the pixel quantum size is only eight bits (quantum range 0 to 255).
Gamma adjusts the image's channel values pixel-by-pixel according to a power law, namely, pow(pixel,1/gamma) or pixel^(1/gamma), where pixel is the normalized or 0 to 1 color value. For example, using a value of gamma=2 is the same as taking the square root of the image.
You can apply separate gamma values to the red, green, and blue channels of the image with a gamma value list delimited with commas (e.g., 1.7,2.3,1.2).
Use +gamma value to set theimage gamma level without actually adjusting the image pixels. This optionis useful if the image is of a known gamma but not set as an image attribute(e.g. PNG images). Write the "file gamma" which is the reciprocal of thedisplay gamma; e.g., if your image is sRGB and you want to write a PNG gAMAchunk, use
$ convert input.png +gamma .45455 output.png
(0.45455 is 1/2.2)Note that gamma adjustments are also available via the -level operator.
Blur the image with a Gaussian operator. |
Convolve the image with a Gaussian or normal distribution using the givenSigma value. The formula is:

The Sigma value is the important argument, anddetermines the actual amount of blurring that will take place.
The Radius is only used to determine the size of thearray which will hold the calculated Gaussian distribution. It should be aninteger. If not given, or set to zero, IM will calculate the largest possibleradius that will provide meaningful results for the Gaussian distribution.
The larger the Radius the radius the slower theoperation is. However too small a Radius, and severaliasing effects may result. As a guideline, Radiusshould be at least twice the Sigma value, though threetimes will produce a more accurate result.
This differs from the faster -blur operator in that afull 2-dimensional convolution is used to generate the weighted average of theneighboring pixels.
The -virtual-pixel setting will determine howpixels which are outside the image proper are blurred into the final result.
Set the preferred size and location of the image. |
See Image Geometry for complete details about the geometry argument.
Sets the current gravity suggestion for various other settings and options. |
Choices include: NorthWest, North, NorthEast,West, Center, East, SouthWest,South, SouthEast. Use -list gravity to get a completelist of -gravity settings available in your ImageMagickinstallation.
The direction you choose specifies where to position text or subimages. For example, a gravity of Center forces the text to be centered within the image. By default, the image gravity is NorthWest. See -draw for more details about graphic primitives. Only the text primitive of -draw is affected by the -gravity option.
The -gravity option is also used in concert with the -geometry setting and other settings or options that take geometry as an argument, such as the -crop option.
If a -gravity setting occurs before another option or setting having a geometry argument that specifies an offset, the offset is usually applied to the point within the image suggested by the -gravity argument. Thus, in the following command, for example, suppose the file image.png has dimensions 200x100. The offset specified by the argument to -region is (−40,+20). The argument to -gravity is Center, which suggests the midpoint of the image, at the point (100,50). The offset (−40,20) is applied to that point, giving (100−40,50+20)=(60,70), so the specified 10x10 region is located at that point. (In addition, the -gravity affects the region itself, which is centered at the pixel coordinate (60,70). (See Image Geometry for complete details about the geometry argument.)
$ convert image.png -gravity Center -region 10x10-40+20 \
-negate output.png
When used as an option to composite, -gravity gives the direction that the image gravitates within the composite.
When used as an option to montage, -gravity gives the direction that an image gravitates within a tile. The default gravity is Center for this purpose.
green chromaticity primary point. |
apply a Hald color lookup table to the image. |
A Hald color lookup table is a 3-dimensional color cube mapped to 2dimensions. Create it with the HALD: prefix (e.g. HALD:8). Youcan apply any color transformation to the Hald image and then use this optionto apply the transform to the image.
$ convert image.png hald.png -hald-clut transform.png
This option provides a convenient method for you to use Gimp or Photoshopto make color corrections to the Hald CLUT image and subsequently apply themto multiple images using an ImageMagick script.
Note that the representation is only of the normal RGB color space and thatthe whole color value triplet is used for the interpolated lookup of therepresented Hald color cube image. Because of this the operation is not
See also -clut which provides color value replacementof the individual color channels, usually involving a simpler gray-scaleimage. E.g: gray-scale to color replacement, or modification by a histogrammapping.
print usage instructions. |
when comparing images, emphasize pixel differences with this color. |
specify the icon geometry. |
Offsets, if present in the geometry specification, are handled in the same manner as the -geometry option, using X11 style to handle negative offsets.
See Image Geometry for complete details about the geometry argument.
iconic animation. |
identify the format and characteristics of the image. |
This information is printed: image scene number; image name; image size; the image class (DirectClass or PseudoClass); the total number of unique colors; and the number of seconds to read and transform the image. Refer to MIFF for a description of the image class.
If -colors is also specified, the total unique colors in the image and color reduction error values are printed. Refer to color reduction algorithm for a description of these values.
If -verbose precedes this option, copiousamounts of image properties are displayed including image statistics, profiles,image histogram, and others.
implements the inverse discrete Fourier transform (DFT). |
This option is new as of ImageMagick 6.5.4-3 (and now working for Windows users in ImageMagick 6.6.0-9). It transforms a pair of magnitude and phase images from the frequency domain to a single image in the normal or spatial domain. See for example, Fourier Transform, Discrete Fourier Transform and Fast Fourier Transform.
For example, depending upon the image format used to store the result of the -fft, one would use either
$ convert fft_image.miff -ift fft_image_ift.png
or
$ convert fft_image-0.png fft_image-1.png -ift fft_image_ift.png
The resulting image may need to be cropped due to padding introduced when the original image, prior to the -fft or +fft, was not square or even dimensioned. Any padding is at the right and/or bottom sides of the image.
The FFTW delegate library is required to use -ift.
Use +ift (with HDRI enabled) to transform a pair of real and imaginary images from the frequency domain to a single image in the normal (spatial) domain.
make image immutable. |
implode image pixels about the center. |
insert the last image into the image sequence. |
This option takes last image in the current image sequence and inserts it at the given index. If a negative index is used, the insert position is calculated before the last image is removed from the sequence. As such -insert -1 will result in no change to the image sequence.
The +insert option is equivalent to -insert -1. In other words, insert the last image, at the end of the current image sequence. Consequently this has no effect on the image sequence order.
use this type of rendering intent when managing the image color. |
Use this option to affect the color management operation of an image (see -profile). Choose from these intents: Absolute, Perceptual, Relative, Saturation.
The default intent is undefined.
To print a complete list of rendering intents, use -list intent.
the type of interlacing scheme. |
Choose from:
none line plane partition JPEG GIF PNG
This option is used to specify the type of interlacing scheme for raw image formats such as RGB or YUV.
None means do not interlace (RGBRGBRGBRGBRGBRGB...),
Line uses scanline interlacing (RRR...GGG...BBB...RRR...GGG...BBB...), and.
Plane uses plane interlacing (RRRRRR...GGGGGG...BBBBBB...).
Partition is like plane except the different planes are saved to individual files (e.g. image.R,image.G, and image.B).
Use Line or Plane to create an interlaced PNG or GIF or progressive JPEGimage.
To print a complete list of interlacing schemes, use -list interlace.
Set the pixel color interpolation method to use when looking up a color based on a floating point or real value. |
When looking up the color of a pixel using a non-integer floating pointvalue, you typically fall in between the pixel colors defined by the sourceimage. This setting determines how the color is determined from the colors ofthe pixels surrounding that point. That is how to determine the color of apoint that falls between two, or even four different colored pixels.
integer The color of the top-left pixel (floor function) nearest-neighbor The nearest pixel to the lookup point (rounded function) average The average color of the surrounding four pixels bilinear A double linear interpolation of pixels (the default) mesh Divide area into two flat triangular interpolations bicubic Fitted bicubic-spines of surrounding 16 pixels spline Direct spline curves (colors are blurred) filter Use resize -filter settings
This most important for distortion operators such as -distort, -implode, -transform and -fx.
To print a complete list of interpolation methods, use -list interpolate.
See also -virtual-pixel, for control of thelookup for positions outside the boundaries of the image.
the space between two text lines. |
the space between two words. |
the space between two letters. |
assign a label to an image. |
Use this option to assign a specific label to the image, as it is read inor created. You can use the -set operation to re-assigna the labels of images already read in. Image formats such as TIFF, PNG,MIFF, supports saving the label information with the image.
When saving an image to a PostScript file, any labelassigned to an image is used as a header string to print above the postscriptimage.
You can include the image filename, type, width, height, or other imageattribute by embedding special format character. See Format and Print ImageProperties for details of the percent escape codes.
For example,
-label "%m:%f %wx%h" bird.miff
assigns an image label of MIFF:bird.miff 512x480 to the"bird.miff" image and whose width is 512 and height is 480, as itis read in. If a +label option was used instead, anyexisting label present in the image would be used. You can remove all labelsfrom an image by assigning the empty string.
A label is not drawn on the image, but is embedded in the image datastreamvia Label tag or similar mechanism. If you want the label to bevisible on the image itself, use the -draw option, orduring the final processing in the creation of a image montage.
If the first character of string is
perform local adaptive threshold. |
Adaptively threshold each pixel based on the value of pixels in asurrounding window. If the current pixel is lighter than this average plusthe optional offset, then it is made white, otherwise it is madeblack. Small variations in pixel values such as found in scanned documentscan be ignored if offset is positive. A negative offset will make it moresensitive to those small variations.
This is commonly used to threshold images with an uneven background. It isbased on the assumption that average color of the small window is thethe local background color, from which to separate the foreground color.
handle multiple images forming a set of image layers or animation frames. |
Perform various image operation methods to a ordered sequence of imageswhich may represent either a set of overlaid 'image layers', a GIF disposalanimation, or a fully-'coalesced' animation sequence.
Method | Description |
---|---|
compare-any | Crop the second and later frames to the smallest rectangle that contains all the differences between the two images. No GIF -dispose methods are taken into account. |
This exactly the same as the -deconstruct operator, and does not preserve animations normal working, especially when animation used layer disposal methods such as 'Previous' or 'Background'. | |
compare-clear | As 'compare-any' but crop to the bounds of any opaque pixels which become transparent in the second frame. That is the smallest image needed to mask or erase pixels for the next frame. |
compare-overlay | As 'compare-any' but crop to pixels that add extra color to the next image, as a result of overlaying color pixels. That is the smallest single overlaid image to add or change colors. |
This can be used with the -compose alpha composition method 'change-mask', to reduce the image to just the pixels that need to be overlaid. | |
coalesce | Equivalent to a call to the -coalesce operator. Apply the layer disposal methods set in the current image sequence to form a fully defined animation sequence, as it should be displayed. Effectively converting a GIF animation into a 'film strip'-like animation. |
composite | Alpha Composition of two image lists, separated by a "null:" image, with the destination image list first, and the source images last. An image from each list are composited together until one list is finished. The separator image and source image lists are removed. |
The -geometry offset is adjusted according to -gravity in accordance of the virtual canvas size of the first image in each list. Unlike a normal -composite operation, the canvas offset is also added to the final composite positioning of each image. | |
If one of the image lists only contains one image, that image is applied to all the images in the other image list, regardless of which list it is. In this case it is the image meta-data of the list which preserved. | |
dispose | This like 'coalesce' but shows the look of the animation after the layer disposal method has been applied, before the next sub-frame image is overlaid. That is the 'dispose' image that results from the application of the GIF -dispose method. This allows you to check what is going wrong with a particular animation you may be developing. |
flatten | Create a canvas the size of the first images virtual canvas using the current -background color, and -compose each image in turn onto that canvas. Images falling outside that canvas is clipped. Final image will have a zero virtual canvas offset. |
This usually used as one of the final 'image layering' operations overlaying all the prepared image layers into a final image. | |
For a single image this method can also be used to fillout a virtual canvas with real pixels, or to underlay an opaque color to remove transparency from an image. | |
merge | As 'flatten' method but merging all the given image layers to create a new layer image just large enough to hold all the image without clipping or extra space. The new images virtual offset will preserve the position of the new layer, even if this offset is negative. The virtual canvas size of the first image is preserved. |
Caution is advised when handling image layers with negative offsets as few image file formats handle them correctly. Following this operation method with +repage will remove the layer offset, and create a image in which all the overlaid image positions relative to each other is preserved, though not necessarily exactly where you specified them. | |
See also 'trim-bounds' below which is closely related but without doing the'flatten' to merge the images together. | |
mosaic | As 'flatten' method but expanding the initial canvas size of the first image in a positive direction only so as to hold all the image layers. However as a virtual canvas is 'locked' to the origin, by its own definition, image layers with a negative offsets will still become clipped by the top and left edges. See 'merge' or 'trim-bounds' if this could be a problem. |
This method is commonly used to layout individual image using various offset but without knowing the final canvas size. The resulting image will, like 'flatten' not have any virtual offset, so can be saved to any image file format. | |
optimize | Optimize a coalesced animation, into GIF animation using a number of general techniques. This currently a short cut to apply both the 'optimize-frame', and 'optimize-transparency' methods but may be expanded to include other optimization methods as they are developed. |
optimize-frame | Optimize a coalesced animation, into GIF animation by reducing the number of pixels per frame as much as possible by attempting to pick the best layer disposal method to use, while ensuring the result will continue to animate properly. |
There is no guarantee that the best optimization is found. But then no reasonably fast GIF optimization algorithm can do this. However this does seem to do better than most other GIF frame optimizers seen. | |
optimize-plus | As 'optimize-frame' but attempt to improve the overall optimization by adding extra frames to the animation, without changing the final look or timing of the animation. The frames are added to attempt to separate the clearing of pixels from the overlaying of new additional pixels from one animation frame to the next. If this does not improve the optimization (for the next frame only), it will fall back to the results of the previous normal 'optimize-frame' technique. |
There is the possibility that the change in the disposal style will result in a worsening in the optimization of later frames, though this is unlikely. In other words there no guarantee that it is better than the normal 'optimize-frame' technique. For some animations however you can get a vast improvement in the final animation size. | |
optimize-transparency | Given a GIF animation, replace any pixel in the sub-frame overlay images with transparency, if it does not change the resulting animation by more than the current -fuzz factor. |
This should allow a existing frame optimized GIF animation to compress into a smaller file size due to larger areas of one (transparent) color rather than a pattern of multiple colors repeating the current disposed image of the last frame. | |
remove-dups | Remove (and merge time delays) of duplicate consecutive images, so as to simplify layer overlays of coalesced animations. |
Usually this a result of using a constant time delay across the whole animation, or after a larger animation was split into smaller sub-animations. The duplicate frames could also have been used as part of some frame optimization methods. | |
remove-zero | Remove any image with a zero time delay, unless ALL the images have a zero time delay (and is not a proper timed animation, a warning is then issued). |
In a GIF animation, such images are usually frames which provide partial intermediary updates between the frames that are actually displayed to users. These frames are usually added for improved frame optimization in GIF animations. | |
trim-bounds | Find the bounds of all the images in the current image sequence, then adjust the offsets so all images are contained on a minimal positive canvas. None of the image data is modified or merged, only the individual image virtual canvas size and offset. All the images is given the same canvas size, and and will have a positive offset, but will remain in the same position relative to each other. As a result of the minimal canvas size at least one image will touch every edge of that canvas. The image data touching those edges however may be transparent. |
The result is much like if you used 'merge' followed by a +repage option, except that all the images have been kept separate. If 'flatten' is used after using 'trim-bounds' you will get the same result. |
To print a complete list of layer types, use -list layers.
The operators -coalesce, -deconstruct, -flatten, and -mosaic are only aliases for the above methods and may be depreciated inthe future. Also see -page, -repage operators, the -compose setting, and theGIF -dispose and -delaysettings.
adjust the level of image channels. |
Given one, two or three values delimited with commas: black-point,white-point, gamma (for example: 10,250,1.0 or 2%,98%,0.5). The black andwhite points range from 0 to QuantumRange, or from 0 to 100%; if the whitepoint is omitted it is set to (QuantumRange - black_point), so as to centercontrast changes. If a % sign is present anywhere in the string,both black and white points are percentages of the full color range. Gammawill do a -gamma adjustment of the values. If it isomitted, the default of 1.0 (no gamma correction) is assumed.
In normal usage (-level) the image values are stretched so thatthe given 'black_point' value in the original image is set tozero (or black), while the given 'white_point' value is set toQuantumRange (or white). This provides you with direct contrast adjustmentsto the image. The 'gamma' of the resulting image will then beadjusted.
From ImageMagick v6.4.1-9 using the plus form of the operator (+level) oradding the special '!' flag anywhere in the argument list, will cause theoperator to do the reverse of the level adjustment. That is a zero, orQuantumRange value (black, and white, resp.) in the original image, isadjusted to the given level values, allowing you to de-contrast, or compressthe channel values within the image. The 'gamma' is adjusted before the level adjustment to de-contrast the image is made.
Only the channels defined by the current -channelsetting are adjusted (defaults to RGB color channels only), allowing you tolimit the effect of this operator.
Please note that the transparency channel is treated as 'matte'values (0 is opaque) and not as 'alpha' values (0 is transparent).
adjust the level of an image using the provided dash separated colors. |
This function is exactly like -level, except that thevalue value for each color channel is determined by the'black_color' and 'white_color' colors given (asdescribed under the -fill option).
This effectually means the colors provided to -level-colorsis mapped to become 'black' and 'white' respectively, with all the othercolors linearly adjusted (or clipped) to match that change. Each channel isadjusted separately using the channel values of the colors specified.
On the other hand the plus form of the operator (+level-colors)will map the image color 'black' and 'white' to the given colorsrespectively, resulting in a gradient (de-contrasting) tint of the image tothose colors. This can also be used to convert a plain gray-scale image into aone using the gradient of colors specified.
By supplying a single color with a comma separator either before or afterthat color, will just replace the respective 'black' or 'white' pointrespectively. But if no comma separator is provided, the given color isused for both the black and white color points, making the operator eitherthreshold the images around that color (- form) or set all colors to thatcolor (+ form).
Set the pixel cache resource limit. |
Choose from: area, disk, file, map, memory, threads, or time.
The value for file is in number of files. The other limits are in bytes. Define arguments for the memory, map, area, and disk resource limits with SI prefixes (.e.g 100MB).
By default the limits are 768 files, 2GB of image area, 1.5GiB memory, 8GiB memory map, and 18.45EB of disk. These limits are adjusted relative to the available resources on your computer if this information is available. When any limit is reached, ImageMagick fails in some fashion but attempts to take compensating actions, if possible. For example, the following limits memory:
-limit memory 32MiB -limit map 64MiB
Use -list resource to list the current limits. For example, our system shows these limits:
$ identify -list resource
File Area Memory Map Disk Thread Time ------------------------------------------------------------------------------ 768 12.404GB 8.6642GiB 23.104GiB 18.446744EB 8 unlimited
Requests for pixel storage to keep intermediate images are satisfied by one of three resource categories: in-memory pool, memory-mapped files pool, and disk pool (in that order) depending on the ‑limit settings and whether the system honors a resource request. If the total size of allocated pixel storage in the given pool reaches the corresponding limit, the request is passed to the next pool. Additionally, requests that exceed the area limit automagically are allocated on disk.
To illustrate how ImageMagick utilizes resource limits, consider a typical image resource request. First, ImageMagick tries to allocate the pixels in memory. The request might be denied if the resource request exceeds the memory limit or if the system does not honor the request. If a memory request is not honored, the pixels are allocated to disk and the file is memory-mapped. However, if the allocation request exceeds the map limit, the resource allocation goes to disk. In all cases, if the resource request exceeds the area limit, the pixels are automagically cached to disk. If the disk has a hard limit, the program fails.
In most cases you simply do not need to concern yourself with resource limits. ImageMagick chooses reasonable defaults and most images do not tax your computer resources. Where limits do come in handy is when you process images that are large or on shared systems where ImageMagick can consume all or most of the available memory. In this case, the ImageMagick workflow slows other processes or, in extreme cases, brings the system to a halt. Under these circumstances, setting limits give some assurances that the ImageMagick workflow will not interfere with other concurrent uses of the computer. For example, assume you have a web interface that processes images uploaded from the Internet. To assure ImageMagick does not exceed 10mb of memory you can simply set the area limit to 10mb:
-limit area 10mb
Now whenever a large image is processed, the pixels are automagically cached to disk instead of memory. This of course implies that large images typically process very slowly, simply because pixel processing in memory can be an order of magnitude faster than on disk. Because your web site users might inadvertently upload a huge image to process, you should set a disk limit as well:
-limit area 10mb -limit disk 500mb
Here ImageMagick stops processing if an image requires more than 500MB of disk storage.
In addition to command-line resource limit option, resources can be set with environment variables. Set the environment variables MAGICK_AREA_LIMIT, MAGICK_DISK_LIMIT, MAGICK_FILE_LIMIT, MAGICK_MEMORY_LIMIT, MAGICK_MAP_LIMIT, MAGICK_THREAD_LIMIT, MAGICK_TIME_LIMIT for limits of image area, disk space, open files, heap memory, memory map, number of threads of execution, and maximum elapsed time in seconds respectively.
Inquisitive users can try adding -debug cache to their commands and then scouring the generated output for references to the pixel cache, in order to determine how the pixel cache was allocated and how resources were consumed. Advanced Unix/Linux users can pipe that output through grep memory|open|destroy|disk for more readable sifting.
For more about ImageMagick's use of resources, see the section Cache Storage and Resource Requirements on the Architecture page.
Linear with saturation stretch. |
This is very similar to -contrast-stretch,and uses a 'histogram bin' to determine the range of color values that needs tobe stretched. However it then stretches those colors using the
As such while the initial determination may have 'binning' round offeffects, the image colors are stretched mathematically, rather than using thehistogram bins. This makes the operator more accurate.
note however that a -linear-stretch of'0' does nothing, while a value of '1' does a nearperfect stretch of the color range.
See also -auto-level for a 'perfect'normalization of mathematical images.
This operator is under review for re-development.
the line width for subsequent draw operations. |
rescale image with seam-carving. |
See Image Geometry for complete details about the geometry argument.
Print a list of supported arguments for various options or settings. Choose from these list types: |
Align Alpha Boolean Channel Class ClipPath Coder Color Colorspace Command Compose Compress Configure DataType Debug Decoration Delegate Direction Dispose Distort Dither Endian Evaluate FillRule Filter Font Format Function Gravity ImageList Intent Interlace Interpolate Kernel Layers LineCap LineJoin List Locale LogEvent Log Magic Method Metric Mime Mode Morphology Module Noise Orientation Policy PolicyDomain PolicyRights Preview Primitive QuantumFormat Resource SparseColor Storage Stretch Style Threshold Type Units Validate VirtualPixel
These lists vary depending on your version of ImageMagick. Use "-listlist" to get a complete listing of all the "-list" argumentsavailable:
$ identify -list list
Specify format for debug log. |
This option specifies the format for the log printed when the
You can display the following components by embedding special formatcharacters:
%d domain %e event %f function %l line %m module %p process ID %r real CPU time %t wall clock time %u user CPU time %% percent sign \n newline \r carriage return
For example:
$ convert -debug coders -log "%u %m:%l %e" in.gif out.png
The default behavior is to print all of the components.
add Netscape loop extension to your GIF animation. |
Set iterations to zero to repeat the animation an infinite number of times,otherwise the animation repeats itself up to iterationstimes.
when comparing images, de-emphasize pixel differences with this color. |
magnify the image. |
Display image using this type. | [animate, display] |
Choose from these Standard Colormap types:
best default gray red green blue
The X server must support the StandardColormap you choose, otherwise an error occurs. Use list asthe type and display searches the list of colormap types intop-to-bottom order until one is located. See
pixel map. | [stream] |
Here are the valid components of a map:
r red pixel component g green pixel component b blue pixel component a alpha pixel component (0 is transparent) o opacity pixel component (0 is opaque) i grayscale intensity pixel component c cyan pixel component m magenta pixel component y yellow pixel component k black pixel component p pad component (always 0)
You can specify as many of these components as needed in any order (e.g.bgr). The components can repeat as well (e.g. rgbr).
Prevent updates to image pixels specified by the mask. |
This the same as using a mask used for composite masking operations, withgrayscale values causing blended updates of the image the mask is attached to.
Use +mask to remove the mask from images.
Also see -clip-mask which work in the same way,but with strict boolean masking.
Specify the color to be used with the -frame option. |
The color is specified using the format described under the -fill option.
The default matte color is #BDBDBD,
return the maximum intensity of an image sequence. |
Select the 'maximum' value from all the surrounding pixels.
This is legacy option from the method of the samename.
apply a median filter to the image. |
Select the 'middle' value from all the surrounding pixels.
This is legacy option from the method of the samename.
Output to STDERR a measure of the differences between images according to the type given metric. |
Choose from:
AE absolute error count, number of different pixels (-fuzz effected) FUZZ mean color distance MAE mean absolute error (normalized), average channel error distance MEPP mean error per pixel (normalized mean error, normalized peak error) MSE mean error squared, average of the channel error squared NCC normalized cross correlation PAE peak absolute (normalize peak absolute) PSNR peak signal to noise ratio RMSE root mean squared (normalized root mean squared)
Control the 'AE', or absolute count of pixels that are different,with the -fuzz factor (ignore pixels whichonly changed by a small amount). Use 'PAE' to find thesize of the -fuzz factor needed to make all pixels'similar', while 'MAE' determines the factor neededfor about half the pixels to be similar.
The 'MEPP' metric returns three different metrics('MAE', 'MAE' normalized, and 'PAE'normalized) from a single comparison run.
To print a complete list of metrics, use the -listmetrics option.
return the minimum intensity of an image sequence. |
Select the 'minimal' value from all the surrounding pixels.
This is legacy option from the method of the samename.
make each pixel the 'predominant color' of the neighborhood. | [convert, mogrify] |
-mode value
Mode of operation. | [montage] |
Choose the value from these styles: Frame,Unframe, or Concatenate
Use the -list option with a 'Mode' argumentfor a list of -mode arguments available in yourImageMagick installation.
Vary the brightness, |
The arguments are given as a percentages of variation. A value of 100 meansno change, and any missing values are taken to mean 100.
The brightness is a multiplier of the overallbrightness of the image, so 0 means pure black, 50 is half as bright, 200 istwice as bright. To invert its meaning -negate the imagebefore and after.
The saturation controls the amount of color in animage. For example, 0 produce a grayscale image, while a large value such as200 produce a very colorful, 'cartoonish' color.
The hue argument causes a "rotation" of the colorswithin the image by the amount specified. For example, 50 results ina counter-clockwise rotation of 90, mapping red shades to purple, and so on.A value of either 0 or 200 results in a complete 180 degree rotation of theimage. Using a value of 300 is a 360 degree rotation resulting in no change tothe original image.
For example, to increase the color brightness by 20% and decrease the colorsaturation by 10% and leave the hue unchanged, use
Use -set attribute of '
$ convert image.png -set option:modulate:colorspace hsb -modulate 120,90 modulate.png
monitor progress. |
transform the image to black and white. |
morphs an image sequence. |
Both the image pixels and size are linearly interpolated to give theappearance of a metamorphosis from one image to the next, over all the imagesin the current image list. The added images are the equivalent of a
apply a morphology method to the image. |
Until I get around to writing an option summary for this, see
an simple alias for the -layers method "mosaic" |
simulate motion blur. |
Blur with the given radius, standard deviation (sigma), and angle. Theangle given is the angle toward which the image is blurred. That is thedirection people would consider the object is coming from.
Note that the blur is not uniform distribution, giving the motion adefinite sense of direction of movement.
The -virtual-pixel setting will determine howpixels which are outside the image proper are blurred into the final result.
name an image. |
replace each pixel with its complementary color. |
The red, green, and blue intensities of an image are negated. White becomes black, yellow becomes blue, etc. Use +negate to only negate the grayscale pixels of the image.
Add or reduce noise in an image. |
The principal function of noise peak elimination filter is to smooth the objects within an image without losing edge information and without creating undesired structures. The central idea of the algorithm is to replace a pixel with its next neighbor in value within a pixel window, if this pixel has been found to be noise. A pixel is defined as noise if and only if this pixel is a maximum or minimum within the pixel window.
Use -noise radius to specify the width of the neighborhood when reducing noise.
Use +noise followed by a noise type to add noise to an image. Choose from these noise types:
Gaussian Impulse Laplacian Multiplicative Poisson Random Uniform
To print a complete list of noises, use the -list noise option.
Also see the -evaluate noise functions that allowsthe use of a controlling value to specify the amount of noise that should beadded to an image.
Increase the contrast in an image by stretching the range of intensity values. |
The intensity values are stretched to cover the entire range of possiblevalues. While doing so, black-out at most 2% of the pixels andwhite-out at most 1% of the pixels.
Note that as of ImageMagick 6.4.7-0, -normalizeis equivalent to -contrast-stretch 2%x1%.(Before this version, it was equivalent to -contrast-stretch 2%x99%).
All the channels are normalized in concert by the came amount so as topreserve color integrity, when the default +channelsetting is in use. Specifying any other -channelsetting will normalize the RGB channels independently.
See -contrast-stretch for more details.Also see -auto-level for a 'perfect' normalizationthat is better suited to mathematically generated images.
This operator is under review for re-development.
dither the image using a pre-defined ordered dither |
You can choose from these standard threshold maps:
threshold 1x1 Threshold 1x1 (non-dither) checks 2x1 Checkerboard 2x1 (dither) o2x2 2x2 Ordered 2x2 (dispersed) o3x3 3x3 Ordered 3x3 (dispersed) o4x4 4x4 Ordered 4x4 (dispersed) o8x8 8x8 Ordered 8x8 (dispersed) h4x4a 4x1 Halftone 4x4 (angled) h6x6a 6x1 Halftone 6x6 (angled) h8x8a 8x1 Halftone 8x8 (angled) h4x4o Halftone 4x4 (orthogonal) h6x6o Halftone 6x6 (orthogonal) h8x8o Halftone 8x8 (orthogonal) h16x16o Halftone 16x16 (orthogonal) c5x5b c5x5 Circles 5x5 (black) c5x5w Circles 5x5 (white) c6x6b c6x6 Circles 6x6 (black) c6x6w Circles 6x6 (white) c7x7b c7x7 Circles 7x7 (black) c7x7w Circles 7x7 (white)
The threshold generated a simple 50% threshold of the image.This could be used with level to do the equivalent of
The checks pattern produces a 3 level checkerboard ditherpattern. That is a grayscale will become a pattern of solid black, solidwhite, and mid-tone colors into a checkerboard pattern of black and white.
You can define your own threshold map for ordereddithering and halftoning your images, in either personal or systemthresholds.xml XML file. See Resourcesfor more details of configuration files.
To print a complete list of the thresholds that have been defined, use the-list threshold option.
Note that at this time the same threshold dithering map is used for allcolor channels, no attempt is made to offset or rotate the map for differentchannels is made, to create an offset printing effect. Also as the maps aresimple threshold levels, the halftone and circle maps will create incompletecircles along the edges of a colored area. Also all the effects are purelyon/off boolean effects, without anti-aliasing to make the circles smoothlooking. Large dots can be made to look better with a small amount of blurringafter being created.
change this color to the fill color within the image. |
The color argument is defined using the formatdescribed under the -fill option. The -fuzz setting can be used to match and replace colors similar to the onegiven.
Use +opaque to paint any pixel that does not matchthe target color.
The -transparent operator is exactly the sameas -opaque but replaces the matching color withtransparency rather than the current -fill color setting.To ensure that it can do this it also ensures that the image has an alphachannel enabled, as per "-alpha set", forthe new transparent colors, and does not require you to modify the
specify orientation of a digital camera image. |
Choose from these orientations:
bottom-left bottom-right left-bottom left-top right-bottom right-top top-left top-right undefined
To print a complete list of orientations, use the -listorientation option.
Set the size and location of an image on the larger virtual canvas. |
See Image Geometry for complete details about the geometry argument.
For convenience you can specify the page size using media (see below). Offsets can then be added as with other geometry arguments (e.g. -page Letter+43+43).
Use media as shorthand to specify the dimensions (widthxheight) of the PostScript page in dots per inch or a TEXT page in pixels. The choices for a PostScript page are:
media | width | height |
---|---|---|
11x17 | 792 | 1224 |
Ledger | 1224 | 792 |
Legal | 612 | 1008 |
Letter | 612 | 792 |
LetterSmall | 612 | 792 |
ArchE | 2592 | 3456 |
ArchD | 1728 | 2592 |
ArchC | 1296 | 1728 |
ArchB | 864 | 1296 |
ArchA | 648 | 864 |
A0 | 2380 | 3368 |
A1 | 1684 | 2380 |
A2 | 1190 | 1684 |
A3 | 842 | 1190 |
A4 | 595 | 842 |
A4Small | 595 | 842 |
A5 | 421 | 595 |
A6 | 297 | 421 |
A7 | 210 | 297 |
A8 | 148 | 210 |
A9 | 105 | 148 |
A10 | 74 | 105 |
B0 | 2836 | 4008 |
B1 | 2004 | 2836 |
B2 | 1418 | 2004 |
B3 | 1002 | 1418 |
B4 | 709 | 1002 |
B5 | 501 | 709 |
C0 | 2600 | 3677 |
C1 | 1837 | 2600 |
C2 | 1298 | 1837 |
C3 | 918 | 1298 |
C4 | 649 | 918 |
C5 | 459 | 649 |
C6 | 323 | 459 |
Flsa | 612 | 936 |
Flse | 612 | 936 |
HalfLetter | 396 | 612 |
This option is also used to place subimages when writing to a multi-image format that supports offsets, such as GIF89 and MNG. When used for this purpose the offsets are always measured from the top left corner of the canvas and are not affected by the -gravity option. To position a GIF or MNG image, use -page{+-}x{+-}y (e.g. -page +100+200). When writing to a MNG file, a -page option appearing ahead of the first image in the sequence with nonzero width and height defines the width and height values that are written in the MHDR chunk. Otherwise, the MNG width and height are computed from the bounding box that contains all images in the sequence. When writing a GIF89 file, only the bounding box method is used to determine its dimensions.
For a PostScript page, the image is sized as in -geometry but positioned relative to the lower left-hand corner of the page by {+-}xoffset{+-}y offset. Use -page 612x792, for example, to center the image within the page. If the image size exceeds the PostScript page, it is reduced to fit the page. The default gravity for the -page option is NorthWest, i.e., positive x and y offset are measured rightward and downward from the top left corner of the page, unless the -gravity option is present with a value other than NorthWest.
The default page dimensions for a TEXT image is 612x792.
This option is used in concert with -density.
Use +page to remove the page settings for an image.
simulate an oil painting. |
Each pixel is replaced by the most frequent color in a circular neighborhood whose width is specified with radius.
write images to this path on disk. |
Pause between animation loops. | [animate] |
Pause for the specified number of seconds before repeating the animation.
Pause between snapshots. | [import] |
Pause for the specified number of seconds before taking the next snapshot.
efficiently determine image characteristics. |
pointsize of the PostScript, OPTION1, or TrueType font. |
simulate a Polaroid picture. |
Use +polaroid to rotate the image at a random angle between -15 and +15 degrees.
reduce the image to a limited number of color levels. |
set the maximum number of significant digits to be printed. |
image preview type. |
Use this option to affect the preview operation of an image (e.g. convert file.png -preview Gamma Preview:gamma.png). Choose from these previews:
Rotate Shear Roll Hue Saturation Brightness Gamma Spiff Dull Grayscale Quantize Despeckle ReduceNoise Add Noise Sharpen Blur Threshold EdgeDetect Spread Shade Raise Segment Solarize Swirl Implode Wave OilPaint CharcoalDrawing JPEG
To print a complete list of previews, use the -list preview option.
The default preview is JPEG.
interpret string and print to console. |
process the image with a custom image filter. |
The command arguments has the form "module arg1 arg2 arg3 ... argN" where module is the name of the module to invoke (e.g. "Analyze") and arg1 arg2 arg3 ... argN are an arbitrary number of arguments to pass to the process module.
Manage ICM, IPTC, or generic profiles in an image. |
Using -profile filename adds an ICM (ICC color management), IPTC (newswire information), or a generic profile to the image.
Use +profile profile_name to remove the indicated profile. ImageMagick uses standard filename globbing, so wildcard expressions may be used to remove more than one profile. Here we remove all profiles from the image except for the XMP profile: +profile "!xmp,*".
Use identify -verbose to find out which profiles are in the image file. Use -strip to remove all profiles (and comments).
To extract a profile, the -profile option is not used. Instead, simply write the file to an image format such as APP1, 8BIM, ICM, or IPTC.
For example, to extract the Exif data (which is stored in JPEG files in the APP1 profile), use.
$ convert cockatoo.jpg profile.exif
It is important to note that results may depend on whether or not the original image already has an included profile. Also, keep in mind that -profile is an "operator" (as opposed to a "setting") and therefore a conversion is made each time it is encountered, in order, in the command-line. For instance, in the following example, if the original image is CMYK with profile, a CMYK-CMYK-RGB conversion results.
$ convert CMYK.tif -profile "CMYK.icc" -profile "RGB.icc" RGB.tiff
Furthermore, since ICC profiles are not necessarily symmetric, extra conversion steps can yield unwanted results.CMYK profiles are often very asymmetric since they involve 3−>4 and 4−>3 channel mapping.
JPEG/MIFF/PNG compression level. |
For the JPEG and MPEG image formats, quality is 1 (lowest image quality andhighest compression) to 100 (best quality but least effective compression).The default is to use the estimated quality of your input image if it canbe determined, otherwise 92. When the quality is greater than 90, then thechroma channels are not downsampled.Use the -sampling-factor option to specify thefactors for chroma downsampling.
For the MIFF image format, quality/10 is the zlib compression level, which is 0 (worst but fastest compression) to 9 (best but slowest). It has no effect on the image appearance, since the compression is always lossless.
For the JPEG-2000 image format, quality is mapped using a non-linear equation to the compression ratio required by the Jasper library. This non-linear equation is intended to loosely approximate the quality provided by the JPEG v1 format. The default quality value 100, a request for non-lossy compression. A quality of 75 results in a request for 16:1 compression.
For the MNG and PNG image formats, the quality value sets the zlibcompression level (quality / 10) and filter-type (quality % 10). The defaultPNG "quality" is 75, which means compression level 7 with adaptive PNGfiltering, unless the image has a color map, in which case it meanscompression level 7 with no PNG filtering.
For compression level 0, the Huffman-only strategy is used, which is fastest but not necessarily the worst compression.
If filter-type is 4 or less, the specified PNG filter-type is used forall scanlines:
0: none 1: sub 2: up 3: average 4: Paeth
If filter-type is 5, adaptive filtering is used when quality is greaterthan 50 and the image does not have a color map, otherwise no filtering isused.
If filter-type is 6, adaptive filteringwith minimum-sum-of-absolute-values is used.
Only if the output is MNG, if filter-type is 7, the LOCO colortransformation (intrapixel differencing) and adaptive filteringwith minimum-sum-of-absolute-values are used.
If the filter-type is 8 the zlib Z_RLE compression strategy is used with no PNG filtering.
If the filter-type is 9 the zlib Z_RLE compression strategy is used with adaptive PNG filtering.
The quality setting has no effect on the appearance or signature of PNGand MNG images, since the compression is always lossless.
Not all combinations of compression level, strategy, and PNG filter typecan be obtained using the -quality option. For more precise control,you can use the PNG:compression-level=N, PNG:compression-strategy=N, andPNG:compression-filter=N defines, respectively, instead.See -define. Values from the defines take precedenceover values from the -quality option.
For further information, seethe PNG specification.
reduce colors using this colorspace. |
This setting defines the colorspace used to sort out and reduce the numberof colors needed by an image (for later dithering) by operators such as
suppress all warning messages. Error messages are still reported. |
Blur around the center of the image. |
Note that this is actually a rotational blur rather than a radial and assuch actually mis-named.
The -virtual-pixel setting will determine howpixels which are outside the image proper are blurred into the final result.
Lighten or darken image edges. |
This will create a 3-D effect. Use -raise to create a raised effect, otherwise use +raise.
Unlike the similar -frame option, -raise does not alter the dimensions of the image.
Apply a random threshold to the image. |
Set the red chromaticity primary point. |
Pay attention to warning messages. |
Reduce the number of colors in an image to the colors used by this image. |
If the -dither setting is enabled (the default) thenthe given colors are dithered over the image as necessary, otherwise the closestcolor (in RGB colorspace) is selected to replace that pixel in the image.
As a side effect of applying a -remap of colors across allimages in the current image sequence, all the images will have the same colortable. That means that when saved to a file format such as GIF, it will usethat color table as a single common or global color table, for all the images,without requiring extra local color tables.
Use +remap to reduce all images in the current imagesequence to use a common color map over all the images. This equivalent toappending all the images together (without extra background colors) and colorreducing those images using -colors with a 256 colorlimit, then -remap those colors over the original list ofimages. This ensures all the images follow a single color map.
If the number of colors over all the images is less than 256, then
Set a region in which subsequent operations apply. |
The x and y offsets are treated in the same manner as in -crop.
See Image Geometry for complete details about the geometry argument.
perform a remote operation. |
The only command recognized is the name of an image file to load.
If you have more than one display application running simultaneously, use the window option to specify which application to control.
render vector operations. |
Use +render to turn off rendering vector operations. This useful when saving the result to vector formats such as MVG or SVG.
Adjust the canvas and offset information of the image. |
This option is like -page but acts as an image operatorrather than a setting. You can separately set the canvas size or the offsetof the image on that canvas by only providing those components.
See Image Geometry for complete details about the geometry argument.
If a ! flag is given the offset given is added to the existingoffset to move the image relative to its previous position. This useful foranimation sequences.
A given a canvas size of zero such as '0x0' forces it torecalculate the canvas size so the image (at its current offset) will appearcompletely on that canvas (unless it has a negative offset).
Use +repage to completely remove/reset the virtualcanvas meta-data from the images.
The -set 'page' option can be used todirectly assign virtual canvas meta-data.
Resample image to specified horizontal and vertical resolution. |
Resize the image so that its rendered size remains the same as the original at the specified target resolution. For example, if a 300 DPI image renders at 3 inches by 2 inches on a 300 DPI device, when the image has been resampled to 72 DPI, it will render at 3 inches by 2 inches on a 72 DPI device. Note that only a small number of image formats (e.g. JPEG, PNG, and TIFF) are capable of storing the image resolution. For formats which do not support an image resolution, the original resolution of the image must be specified via -density on the command line prior to specifying the resample resolution.
Note that Photoshop stores and obtains image resolution from a proprietary embedded profile. If this profile exists in the image, then Photoshop will continue to treat the image using its former resolution, ignoring the image resolution specified in the standard file header.
Resize an image. |
See Image Geometry for complete details about the geometry argument. Offsets, if present in the geometry string, are ignored, and the -gravity option has no effect.
If the -filter option precedes the -resize option, the image is resized with the specified filter.
Many image processing algorithms assume your image is in a linear-light coding. If your image is gamma-corrected, you can remove the nonlinear gamma correction, apply the transform, then restore it like this:
$ convert portrait.jpg -gamma .45455 -resize 25% -gamma 2.2 \
-quality 92 passport.jpg
settings remain in effect until parenthesis boundary. |
Reverse the order of images in the current image list. |
roll an image vertically or horizontally by the amount given. |
A negative x offset rolls the image left-to-right. A negative y offset rolls the image top-to-bottom.
Apply Paeth image rotation (using shear operations) to the image. |
Use > to rotate the image only if its width exceeds the height. < rotates the image only if its width is less than the height. For example, if you specify -rotate "-90>" and the image size is 480x640, the image is not rotated. However, if the image is 640x480, it is rotated by -90 degrees. If you use > or <, enclose it in quotation marks to prevent it from being misinterpreted as a file redirection.
Empty triangles in the corners, left over from rotating the image, arefilled with the background color.
See also the -distort operator and specifically the'ScaleRotateTranslate' distort method.
minify/magnify the image using pixel subsampling and pixel replication, respectively. |
Change the image size simply by directly sampling the pixels originalimage. When magnifying, pixels are replicated in blocks. When minifying,pixels are sub-sampled (i.e., some rows and columns are skipped over).
The results are thus equivalent to using -resize witha -filter setting of point (nearestneighbour), though -sample is a lot faster, as itavoids all the filter processing of the image. As such it completely ignoresthe current -filter setting.
The key feature of the -sample is that no new colorswill be added to the resulting image, though some colors may disappear.
See Image Geometry for complete details about the geometry argument. Offsets, if present in the geometry string, areignored, unlike -resize.
sampling factors used by JPEG or MPEG-2 encoder and YUV decoder/encoder. |
This option specifies the sampling factors to be used by the JPEG encoder for chroma downsampling. If this option is omitted, the JPEG library will use its own default values. When reading or writing the YUV format and when writing the M2V (MPEG-2) format, use -sampling-factor 2x1 or -sampling-factor 4:2:2 to specify the 4:2:2 downsampling method.
minify/magnify the image using pixel block averaging and pixel replication, respectively. |
Change the image size simply by replacing pixels by averaging pixelstogether when minifying, or replacing pixels when magnifying.
The results are thus equivalent to using -resize witha -filter setting of box. Though it is a lotfaster, as it avoids all the filter processing of the image. As such itcompletely ignores the current -filter setting.
If when shrinking (minifying) images the original image is some integermultiple of the new image size, the number of pixels averaged together toproduce the new pixel color is the same across the whole image. This isa special case known as 'binning' and is often used as a method of reducingnoise in image such as those generated by digital cameras, especially in lowlight conditions.
set scene number. |
This option sets the scene number of an image or the first image in an image sequence.
specify the screen to capture. |
This option indicates that the GetImage request used to obtain the image should be done on the root window, rather than directly on the specified window. In this way, you can obtain pieces of other windows that overlap the specified window, and more importantly, you can capture menus or other popups that are independent windows but appear over the specified window.
seed a new sequence of pseudo-random numbers |
segment the colors of an image. |
Segment an image by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique. This is part of the ImageMagick color quantization routines.
Specify cluster threshold as the number of pixels in each cluster that must exceed the cluster threshold to be considered valid. Smoothing threshold eliminates noise in the second derivative of the histogram. As the value is increased, you can expect a smoother second derivative. The default is 1.5.
If the -verbose setting is defined, a detailed reportof the color clusters is returned.
Selectively blur pixels within a contrast threshold. |
Blurs those pixels that are less than or equal to the threshold in contrast. The threshold may be expressed as a fraction of QuantumRange or as a percentage.
separate an image channel into a grayscale image. Specify the channel with -channel. |
simulate a sepia-toned photo. |
Specify threshold as the percent threshold of the intensity (0 - 99.9%).
This option applies a special effect to the image, similar to the effect achieved in a photo darkroom by sepia toning. Threshold ranges from 0 to QuantumRange and is a measure of the extent of the sepia toning. A threshold of 80% is a good starting point for a reasonable tone.
sets image attributes and properties for images in the currentimage sequence. |
This will assign (or modify) specific settings attached to all the imagesin the current image sequence. Using the +set form of theoption will either remove, or reset that setting to a default state, asappropriate.
For example, it will modify specific well known image meta-data'attributes' such as those normally overridden by: the options
If the given key does not match a specific known'attribute ', such as shown above, the setting is stored as a a free form'property' string. Such settings are listed in -verbose information ("info:" output format) as "Properties".
This includes string 'properties' that are set by and assigned to imagesusing the options -comment, -label, -caption. These options actually assigna global 'artifact' which are automatically assigned (and any Format PercentEscapes expanded) to images as they are read in. For example:
$ convert rose: -set comment 'Rose is a rose is a rose is a rose' rose.pngidentify -format %c rose.png $ Rose is a rose is a rose is a rose
The set value can also make use of Format and Print ImageProperties in the defined value. For example:
$ convert rose: -set origsize '%wx%h' -resize 50% \ -format 'Old size = %[origsize] New size = %wx%h' info: $ Old size = 70x46 New size = 35x23
Other well known 'properties' that are availible include:'date:create' and 'date:modify' and'signature'.
The -repage operator will also allow you to modifythe 'page' attribute of an image for images already in memory (alsosee -page). However it is designed to provide a finercontrol of the sub-parts of this 'attribute'. The -set pageoption will only provide a direct, unmodified assignment of 'page'attribute.
This option can also associate a colorspace or profile with your image.For example,
$ convert image.psd -set profile ISOcoated_v2_eci.icc image-icc.psd
Some 'properties' must be defined in a specific way to be used. Forexample only 'properties' prefixed with "filename:" can be used tomodify the output filename of an image. For example
$ convert rose: -set filename:mysize '%wx%h' 'rose_%[filename:mysize].png'
If the setting value is prefixed with "option:" the setting willbe saved as a global "Artifact" exactly as if it was set using the
$ convert rose: -set option:rosesize '%wx%h' -delete 0 \ label:'%[rosesize]' label_size_of_rose.gif
Note that Format Percent Escapes will only matcha 'artifact' if the given key does not match an existing'attribute' or 'property'.
You can set the attributes of the image registry by prefixing the valuewith registry:.
The -set profile option can also be used to injectpreviously-formatted ancillary chunks into the output PNG file, usingthe commandline option as shown below or by setting the profile via aprogramming interface:
$ convert in.png -set profile PNG-chunk-x:<filename> out.png
where x is a location flag andfilename is a file containing the chunkname in the first 4 bytes, then a colon (":"), followed by the chunk data.This encoder will compute the chunk length and CRC, so those must notbe included in the file.
"x" can be "b" (before PLTE), "m" (middle, i.e., between PLTE and IDAT),or "e" (end, i.e., after IDAT). If you want to write multiple chunksof the same type, then add a short unique string after the "x" to preventsubsequent profiles from overwriting the preceding ones, e.g.,
$ convert in.png -set profile PNG-chunk-b01:file01 /
-profile PNG-chunk-b02:file02 out.png
shade the image using a distant light source. |
Specify azimuth and elevation as the position of the light source. Use +shade to return the shading results as a grayscale image.
simulate an image shadow. |
-shared-memory
use shared memory. |
This option specifies whether the utility should attempt to use shared memory for pixmaps. ImageMagick must be compiled with shared memory support, and the display must support the MIT-SHM extension. Otherwise, this option is ignored. The default is True.
sharpen the image. |
Use a Gaussian operator of the given radius and standard deviation (sigma).
Shave pixels from the image edges. |
The size portion of the geometry argument specifies the width of the region to be removed from both sides of the image and the height of the regions to be removed from top and bottom. Offsets are ignored.
See Image Geometry for complete details about the geometry argument.
Shear the image along the x-axis and/or y-axis. |
The shear angles may be positive, negative, or zero. When Ydegrees is omitted it defaults to 0. When both angles are given, the horizontal component of the shear is performed before the vertical component.
Shearing slides one edge of an image along the x-axis or y-axis (i.e., horizontally or vertically, respectively),creating a parallelogram. The amount of each is controlled by the respective shear angle. For horizontal shears, Xdegrees is measured clockwise relative to "up" (the negative y-axis), sliding the top edge to the right when 0°<Xdegrees<90° and to the left when 90°<Xdegrees<180°. For vertical shears Ydegrees is measured clockwise relative to "right" (the positive x-axis), sliding the right edge down when 0°<Ydegrees<90° and up when 90°<Ydegrees<180°.
Empty triangles left over from shearing the image are filled with the color defined by the -background option. The color is specified using the format described under the -fill option.
The horizontal shear is performed before the vertical part. This is important to note, since horizontal and vertical shears do not commute, i.e., the order matters in a sequence of shears. For example, the following two commands are not equivalent.
$ convert logo: -shear 20x0 -shear 0x60 logo-sheared.png $ convert logo: -shear 0x60 -shear 20x0 logo-sheared.png
The first of the two commands above is equivalent to the following, except for the amount of empty space created; the command that follows generates a smaller image, and so is a better choice in terms of time and space.
$ convert logo: -shear 20x60 logo-sheared.png
increase the contrast without saturating highlights or shadows. |
Increase the contrast of the image using a sigmoidal transfer function without saturating highlights or shadows. Contrast indicates how much to increase the contrast. For example, near 0 is none, 3 is typical and 20 is a lot. Note that exactly zero is invalid, but 0.0001 is negligibly different from no change in contrast. mid-point indicates where midtones fall in the resultant image (0 is white; 50% is middle-gray; 100% is black). By default the image contrast is increased, use +sigmoidal-contrast to decrease the contrast.
To achieve the equivalent of a sigmoidal brightness change, use -sigmoidal-contrast brightnessx0% to increase brightness and class="arg">+sigmoidal-contrast brightnessx0% to decrease brightness.
operate silently. |
set the width and height of the image. |
Use this option to specify the width and height of raw images whose dimensions are unknown such as GRAY, RGB, or CMYK. In addition to width and height, use -size with an offset to skip any header information in the image or tell the number of colors in a MAP image file, (e.g. -size 640x512+256).
For Photo CD images, choose from these sizes:
192x128 384x256 768x512 1536x1024 3072x2048
simulate a pencil sketch. |
Sketch with the given radius, standard deviation (sigma), and angle. The angle given is the angle toward which the image is sketched. That is the direction people would consider the object is coming from.
smush an image sequence together. |
Set the number of screen snapshots. | [import] |
Use this option to grab more than one image from the X server screen, to create an animation sequence.
negate all pixels above the threshold level. |
Specify factor as the percent threshold of the intensity (0 - 99.9%).
This option produces a solarization effect seen when exposing a photographic film to light during the development process.
color the given image using the specified points of color, and filling the other intervening colors using the given methods. |
Method | Description |
---|---|
barycentric | three point triangle of color given 3 points. Giving only 2 points will form a linear gradient between those points. The gradient generated extends beyond the triangle created by those 3 points. |
bilinear | Like barycentric but for 4 points. Less than 4 points fall back to barycentric. |
voronoi | Simply map each pixel to the to nearest color point given. The result are polygonal 'cells' of solid color. |
shepards | Colors points biased on the ratio of inverse distance squared. Generating spots of color in a sea of the average of colors. |
inverse | Colors points biased on the ratio of inverse distance. This generates sharper points of color rather than rounded spots of 'shepards' Generating spots of color in a sea of the average of colors. |
The points are placed according to the images location on the virtualcanvas (-page or -repageoffset), and do not actually have to exist on the given image, but may besome point beyond the edge of the image. All points are floating point values.
Only the color channels defined by the -channel aremodified, which means that by default matte/alpha transparency channel is noteffected. Typically transparency channel is turned off either before or afterthe operation.
Of course if some color points are transparent to generate a transparentgradient, then the image also requires transparency enabled to store thevalues.All the above methods when given a single point of color will replace allthe colors in the image with the color given, regardless of the point. This islogical, and provides an alternative technique to recolor a image to somedefault value.
Splice the current background color into the image. |
This will add rows and columns of the current
If the exact same geometry and
displace image pixels by a random amount. |
The argument amount defines the size of the neighborhood around each pixel from which to choose a candidate pixel to swap.
replace each pixel with corresponding statistic from the neighborhood. | [convert, mogrify] |
Choose from these statistic types:
Gradient maximum difference in area Maximum maximum value per channel in neighborhood Minimum minimum value per channel in neighborhood Mean average value per channel in neighborhood Median median value per channel in neighborhood Mode mode (most frequent) value per channel in neighborhood Nonpeak value just before or after the median value per channel in neighborhood
hide watermark within an image. |
Use an offset to start the image hiding some number of pixels from the beginning of the image. Note this offset and the image size. You will need this information to recover the steganographic image (e.g. display -size 320x256+35 stegano:image.png).
composite two images to create a stereo anaglyph. | [composite] |
The left side of the stereo pair is saved as the red channel of the output image. The right side is saved as the green channel. Red-green stereo glasses are required to properly view the stereo image.
pixel storage type. Here are the valid types: |
char unsigned characters double doubles float floats integer integers long longs quantum pixels in the native depth of your ImageMagick distribution short unsigned shorts
Float and double types are normalized from 0.0 to 1.0 otherwise the pixelsvalues range from 0 to the maximum value the storage type can support.
Set a type of stretch style for fonts. |
This setting suggests a type of stretch that ImageMagick should try to apply to the currently selected font family. Select fontStretch from the following.
Any Condensed Expanded ExtraCondensed ExtraExpanded Normal SemiCondensed SemiExpanded UltraCondensed UltraExpanded
To print a complete list of stretch types, use -list stretch.
For other settings that affect fonts, see the options -font, -family, -style, and -weight.
strip the image of any profiles or comments. |
color to use when stroking a graphic primitive. |
The color is specified using the format described under the -fill option.
See -draw for further details.
set the stroke width. |
See -draw for further details.
Set a font style for text. |
This setting suggests a font style that ImageMagick should try to apply tothe currently selected font family. Select fontStyle fromthe following.
Any Italic Normal Oblique
For other settings that affect fonts, see the options -font, -family, -stretch, and -weight.
search for subimage. | [compare] |
This option is required to have compare search for the best match locationof a small image within a larger image. This search will produce two images(or two frames). The first is the "difference" image and the second willbe the "match score" image.
The "match-score" image is smaller containing a pixel for ever possibleposition of the top-left corner of the given sub-image. that is its size willbe the size of the larger_image - sub_image + 1. The brightest location inthis image is the location s the locate on the best match that is alsoreported. Note that this may or may nor be a perfect match, and the actualbrightness will reflect this. Other bright 'peaks' can be used to locate otherpossible matching locations.
Note that the search will try to compare the sub-image at every possiblelocation in the larger image, as such it can be very slow. The smaller thesub-image the faster this search is.
Swap the positions of two images in the image sequence. |
For example, -swap 0,2 swaps the first and the thirdimages in the current image sequence. Use +swap to switchthe last two images in the sequence.
swirl image pixels about the center. |
Degrees defines the tightness of the swirl.
synchronize image to storage device. |
Mark the image as modified. |
font for writing fixed-width text. |
Specifies the name of the preferred font to use in fixed (typewriter style) formatted text. The default is 14 point Courier.
You can tag a font to specify whether it is a PostScript, TrueType, or OPTION1 font. For example, Courier.ttf is a TrueType font and x:fixed is OPTION1.
name of texture to tile onto the image background. |
Apply simultaneous black/white threshold to the image. |
Any pixel values (more specifically, those channels set using ‑channel) that exceed the specified threshold are reassigned the maximum channel value, while all other values are assigned the minimum.
The threshold value can be given as a percentage or as an absolute integer value corresponding to the desired channel value. When given as an integer, the minimum attainable value is 0 (corresponding to black when all channels are affected), but the maximum value (corresponding to white) is that of the quantum depth of the particular build of ImageMagick, and is therefore dependent on the installation. For that reason, a reasonable recommendation for most applications is to specify the threshold values as a percentage.
The following would force pixels with red values above 50% to have 100% red values, while those at or below 50% red would be set to 0 in the red channel. The green, blue, and alpha channels (if present) would be unchanged.
$ convert in.png -channel red -threshold 50% out.png
As (possibly) impractical but instructive examples, the following would generate an all-black and an all-white image with the same dimensions as the input image.
$ convert in.png -threshold 100% black.png $ convert in.png -threshold -1 white.png
Note that the values of the transparency channel is treated as 'matte'values (0 is opaque) and not as 'alpha' values (0 is transparent).
See also ‑black‑threshold and ‑white‑threshold.
Create a thumbnail of the image. |
This is similar to -resize, except it is optimized for speed and any image profile, other than a color profile, is removed to reduce the thumbnail size. To strip the color profiles as well, add -strip just before of after this option.
See Image Geometry for complete details about the geometry argument.
Set the tile image used for filling a subsequent graphic primitive. |
-tile geometry
Specify the layout of images . | [montage] |
See Image Geometry for complete details about the geometry argument.
-tile
Specifies that a subsequent composite operation is repeated across and down image. | [composite] |
Specify the offset for tile images, relative to the background image it is tiled on. |
This should be set before the tiling image is set by -tile or -texture, or directly applied for creating a tiled canvas using TILE: or PATTERN: input formats.
Internally ImageMagick does a -roll of the tile image by the arguments given when the tile image is set.
Tint the image with the fill color. |
Tint the image with the fill color.
Specify the amount of tinting as a percentage. Pure colors like black, white red, yellow, will not be affected by -tint. Only mid-range colors such as the various shades of grey.
Assign a title to displayed image. | [animate, display, montage] |
Use this option to assign a specific title to the image. This assigned to the image window and is typically displayed in the window title bar. Optionally you can include the image filename, type, width, height, Exif data, or other image attribute by embedding special format characters described under the -format option.
For example,
-title "%m:%f %wx%h"
produces an image title of MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.
transform the image. |
This option applies the transformation matrix from a previous -affine option.
$ convert -affine 2,2,-2,2,0,0 -transform bird.ppm bird.jpg
This operator has been now been superseded by the
Make this color transparent within the image. |
The color argument is defined using the formatdescribed under the -fill option. The -fuzz setting can be used to match and replace colors similar to the onegiven.
Use +transparent to invert the pixels matched.that is make all non-matching colors transparent.
The -opaque operator is exactly the same as
Note that this does not define the color as being the 'transparency color'used for color-mapped image formats, such as GIF. For that use
Set the transparent color. |
Sometimes this is used for saving to image formats such asGIF and PNG8 which uses this color to represent boolean transparency. Thisdoes not make a color transparent, it only defines what color the transparentcolor is in the color palette of the saved image. Use
This option allows you to have both an opaque visible color, as well as atransparent color of the same color value without conflict. That is, you canuse the same color for both the transparent and opaque color areas within animage. This, in turn, frees to you to select a transparent color that isappropriate when an image is displayed by an application that does not handle atransparent color index, while allowing ImageMagick to correctly handle images of thistype.
The default transparent color is #00000000, which is fully transparent black.
Mirror the image along the top-left to bottom-right diagonal. |
This option mathematically transposes the pixel array. It is equivalent to the sequence -flip -rotate 90.
Mirror the image along the images bottom-left top-right diagonal. Equivalent to the operations -flop -rotate 90. |
tree depth for the color reduction algorithm. |
Normally, this integer value is zero or one. A value of zero or one causes the use of an optimal tree depth for the color reduction algorithm.
An optimal depth generally allows the best representation of the source image with the fastest computational speed and the least amount of memory. However, the default depth is inappropriate for some images. To assure the best representation, try values between 2 and 8 for this parameter. Refer to the color reduction algorithm for more details.
The -colors or -monochrome option, or writing to an image format which requires color reduction, is required for this option to take effect.
trim an image. |
This option removes any edges that are exactly the same color as the corner pixels. Use -fuzz to make -trim remove edges that are nearly the same color as the corner pixels.
The page or virtual canvas information of the image is preserved allowingyou to extract the result of the -trim operation from theimage. Use a +repage to remove the virtual canvas pageinformation if it is unwanted.
If the trimmed image 'disappears' an warning is produced, and a specialsingle pixel transparent 'missed' image is returned, in the same way as when a-crop operation 'misses' the image proper.
the image type. |
Choose from: Bilevel, Grayscale, GrayscaleMatte, Palette, PaletteMatte, TrueColor, TrueColorMatte, ColorSeparation, or ColorSeparationMatte.
Normally, when a format supports different subformats such as grayscale and truecolor, the encoder will try to choose an efficient subformat. The -type option can be used to override this behavior. For example, to prevent a JPEG from being written in grayscale format even though only gray pixels are present, use.
$ convert bird.png -type TrueColor bird.jpg
Similarly, use -type TrueColorMatte to force the encoder to write an alpha channel even though the image is opaque, if the output format supports transparency.
Use -type optimize to ensure the image is written in the smallest possible file size.
set the color of the annotation bounding box. |
The color is specified using the format described under the -fill option.
See -draw for further details.
detect when image file is modified and redisplay. |
Suppose that while you are displaying an image the file that is currently displayed is over-written. display will automagically detect that the input file has been changed and update the displayed image accordingly.
discard all but one of any pixel color. |
the units of image resolution. |
Choose from: Undefined, PixelsPerInch, or PixelsPerCentimeter. This option is normally used in conjunction with the -density option.
sharpen the image with an unsharp mask operator. |
The -unsharp option sharpens an image. The image is convolved with a Gaussian operator of the given radius and standard deviation (sigma). For reasonable results, radius should be larger than sigma. Use a radius of 0 to have the method select a suitable radius.
The parameters are:
radius The radius of the Gaussian, in pixels, not counting the center pixel (default 0). sigma The standard deviation of the Gaussian, in pixels (default 1.0). amount The fraction of the difference between the original and the blur image that is added back into the original (default 1.0). threshold The threshold, as a fraction of QuantumRange, needed to apply the difference amount (default 0.05).
print detailed information about the image when this option precedes the -identify option or info:. |
print ImageMagick version string and exit. |
FlashPix viewing parameters. |
soften the edges of the image in vignette style. |
Specify contents of virtual pixels. |
This option defines what color source should be used if and when a colorlookup completely 'misses' the source image. The color(s) that appear tosurround the source image. Generally this color is derived from the sourceimage, but could also be set to a specify background color.
Choose from these methods:
background the area surrounding the image is the background color black the area surrounding the image is black checker-tile alternate squares with image and background color dither non-random 32x32 dithered pattern edge extend the edge pixel toward infinity gray the area surrounding the image is gray horizontal-tile horizontally tile the image, background color above/below horizontal-tile-edge horizontally tile the image and replicate the side edge pixels mirror mirror tile the image random choose a random pixel from the image tile tile the image (default) transparent the area surrounding the image is transparent blackness vertical-tile vertically tile the image, sides are background color vertical-tile-edge vertically tile the image and replicate the side edge pixels white the area surrounding the image is white
The default value is "edge".
This most important for distortion operators such as -distort, -implode, and -fx.However it also effects operations that may access pixels just outside theimage proper, such as -convolve,
To print a complete list of virtual pixel types, use the -list virtual-pixel option.
Animate images using this X visual type. | [animate, display] |
Choose from these visual classes:
StaticGray GrayScale StaticColor PseudoColor TrueColor DirectColor default visual id
The X server must support the visual you choose, otherwise an error occurs. If a visual is not specified, the visual class that can display the most simultaneous colors on the default screen is chosen.
Watermark an image using the given percentages of brightness andsaturation. | [composite] |
Take a grayscale image (with alpha mask) and modify the destination image'sbrightness according to watermark image's grayscale value and the
Shear the columns of an image into a sine wave. |
Specify amplitude and wavelength of the wave.
Set a font weight for text. |
This setting suggests a font weight that ImageMagick should try to apply to the currently selected font family. Use a positive integer for fontWeight or select from the following.
fontWeight | Description |
---|---|
All | No effect. |
Bold | Same as fontWeight = 700. |
Bolder | Add 100 to font weight if currently ≤ 800. |
Lighter | Subtract 100 to font weight if currently ≤ 100. |
Normal | Same as fontWeight = 400. |
To print a complete list of weight types, use -list weight.
For other settings that affect fonts, see the options -font, -family, -stretch, and -style.
chromaticity white point. |
Force to white all pixels above the threshold while leaving all pixels at or below the threshold unchanged. |
The threshold value can be given as a percentage or as an absolute integer value within [0, QuantumRange] corresponding to the desired ‑channel value. See ‑threshold for more details on thresholds and resulting values.
Make the image the background of a window. | [animate, display] |
id can be a window id or name. Specify root to select X's root window as the target window.
By default the image is tiled onto the background of the target window. If backdrop or -resize are specified, the image is surrounded by the background color. Refer to X RESOURCES for details.
The image will not display on the root window if the image has more unique colors than the target window colormap allows. Use -colors to reduce the number of colors.
specify the window group. |
write an image sequence. |
The image sequence preceding the -write filename option is written out, and processing continues with the same image in its current state if there are additional options. To restore the image to its original state after writing it, use the +write filename option.
Use -compress to specify the type of image compression.