convert recognizes the following image formats:
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Note, a format delineated with + means that if more than one image is specified, it is combined into a single multi-image file. Use +adjoin if you want a single image produced for each frame.
Raw images are expected to have one byte per pixel unless ImageMagick is compiled in 16-bit mode. Here, the raw data is expected to be stored two bytes per pixel in most-significant-byte-first order.
To convert a MIFF image of a cockatoo to a SUN raster image, use:
convert cockatoo.miff sun:cockatoo.ras
To convert a multi-page Postscript document to individual FAX pages, use:
convert -monochrome document.ps fax:page
To convert a TIFF image to a Postscript A4 page with the image in the lower left-hand corner, use:
convert -page A4+0+0 image.tiff document.ps
To convert a raw GRAY image with a 128 byte header to a portable graymap, use:
convert -size 768x512+128 gray:raw image.pgm
To convert a Photo CD image to a TIFF image, use:
convert -size 1536x1024 img0009.pcd image.tiff
convert img0009.pcd[4] image.tiff
To create a visual image directory of all your JPEG images, use:
convert 'vid:*.jpg' directory.miff
To annotate an image with blue text using font 12x24 at position (100,100), use:
convert -font helvetica -pen blue -draw "text 100,100 Cockatoo" bird.jpg bird.miff
To tile a 640x480 image with a JPEG texture with bumps use:
convert -size 640x480 tile:bumps.jpg tiled.png
To surround an icon with an ornamental border to use with Mosaic(1), use:
convert -mattecolor #ccc -frame 6x6 bird.jpg icon.png
To create a GIF animation image from a DNA molecule sequence, use:
convert -delay 20 dna.* dna.gif
By default, all images of an image sequence are stored in the same file. However, some formats (e.g. JPEG) do not support more than one image and are saved to separate files. Use +adjoin to force this behavior.
The color of the border is specified with the -bordercolor command line option.
See X(1) for details about the color specification.
Specify the amount of colorization as a percentage. You can apply separate colorization values to the red, green, and blue channels of the image with a colorization value list delineated with slashes (e.g. 0/0/50).
The actual number of colors in the image may be less than your request, but never more. Note, this is a color reduction option. Images with less unique colors than specified with this option will have any duplicate or unused colors removed. Refer to quantize(9) for more details.
Note, options -dither, -colorspace, and -treedepth affect the color reduction algorithm.
Color reduction, by default, takes place in the RGB color space. Empirical evidence suggests that distances in color spaces such as YUV or YIQ correspond to perceptual color differences more closely than do distances in RGB space. These color spaces may give better results when color reducing an image. Refer to quantize(9) for more details.
The Transparent color space behaves uniquely in that it preserves the matte channel of the image if it exists.
The -colors or -monochrome option is required for this option to take effect.
By default, each image is commented with its file name. Use this option to assign a specific comment to the image. Optionally you can include the image filename, type, width, height, or scene number by embedding special format characters. Embed %f for filename, %d for directory, %e for filename extention, %t for top of filename, %m for magick, %w for width, %h for height, %s for scene number, %b for file size, or \n for newline. For example,
-comment "%m:%f %wx%h"
produces an image comment of MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.
If the first character of string is @, the image comment is read from a file titled by the remaining characters in the string.
Specify +compress to store the binary image in an uncompressed format. The default is the compression type of the specified image file.
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.
To specify a percentage width or height instead, append %. For example to crop the image by ten percent on all sides of the image, use -crop 10%.
Use cropping to crop a particular area of an image. Use -crop 0x0 to remove edges that are the background color. Omit the x and y offset to generate one or more subimages of a uniform size.
Amount defines the number of positions each colormap entry is shifted.
This option is useful for regulating the animation of a sequence of GIF images within Netscape. 1/100ths of a second must expire before the redisplay of the image sequence. The default is no delay between each showing of the image sequence. The maximum delay is 65535.
This option specifies an image density when decoding a Postscript or Portable Document page. The default is 72 pixels per inch in the horizontal and vertical direction. This option is used in concert with -page.
Here are the valid methods:
0 No disposal specified.
1 Do not dispose.
2 Restore to background color.
3 Restore to previous.
The basic strategy of dithering is to trade intensity resolution for spatial resolution by averaging the intensities of several neighboring pixels. Images which suffer from severe contouring when reducing colors can be improved with this option.
The -colors option is required for dithering to take effect.
Use this option to annotate an image with one or more graphic primitives. The primitives include
point
line
rectangle
fillRectangle
circle
fillCircle
polygon
fillPolygon
color
matte
text
image
Point, line, color, matte, text, and image each require a single coordinate. Line requires a start and end coordinate, while rectangle expects an upper left and lower right coordinate. Circle has a center coordinate and a coordinate on the outer edge. Finally, polygon requires three or more coordinates defining its boundaries. Coordinates are integers separated by an optional comma. For example, to define a circle centered at 100,100 that extends to 150,150 use:
-draw 'circle 100,100 150,150'
Use color to change the color of a pixel. Follow the pixel coordinate with a method:
point
replace
floodfill
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. 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. Finally reset changes the matte value of all pixels.
Use text to annotate an image with text. Follow the text coordinates with a string. If the string has embedded spaces, enclose it in double quotes. Optionally you can include the image filename, type, width, height, or scene number by embedding special format characters. Embed %f for filename, %d for directory, %e for filename extention, %t for top of filename, %m for magick, %w for width, %h for height, %s for scene number, %b for file size, or \n for newline. For example,
-draw 'text 100,100 "%m:%f %wx%h"'
annotates the image with MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.
Use image to composite an image with another image. Follow the image coordinates with the filename of an image.
If the first character of string is @, the text is read from a file titled by the remaining characters in the string.
You can set the primitive color, font color, and font bounding box color with -pen, -font, and -box respectively. Options are processed in command line order so be sure to use -pen before the -draw option.
If the font is a fully qualified X server font name, the font is obtained from an X server (e.g. -*-helvetica-medium-r-*-*-12-*-*-*-*-*-iso8859-*). To use a TrueType font, precede the TrueType filename with a @ (e.g. @times.ttf). Otherwise, specify a Postscript font (e.g. helvetica).
The color of the border is specified with the -mattecolor command line option.
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.
You can apply separate gamma values to the red, green, and blue channels of the image with a gamma value list delineated with slashes (e.g. 1.7/2.3/1.2).
Use +gamma to set the image gamma level without actually adjusting the image pixels. This option is useful if the image is of a known gamma but not set as an image attribute (e.g. PNG images).
By default, the width and height are maximum values. That is, the image is expanded or contracted to fit the width and height value while maintaining the aspect ratio of the image. Append an exclamation point to the geometry to force the image size to exactly the size you specify. For example, if you specify 640x480! the image width is set to 640 pixels and height to 480. If only one factor is specified, both the width and height assume the value.
To specify a percentage width or height instead, append %. The image size is multiplied by the width and height percentages to obtain the final image dimensions. To increase the size of an image, use a value greater than 100 (e.g. 125%). To decrease an image's size, use a percentage less than 100.
Use > to change the dimensions of the image only if its size exceeds the geometry specification. < resizes the image only if its dimensions is less than the geometry specification. For example, if you specify 640x480> and the image size is 512x512, the image size does not change. However, if the image is 1024x1024, it is resized to 640x480.
There are 72 pixels per inch in Postscript coordinates.
This option is used to specify the type of interlacing scheme for raw image formats such as RGB or YUV. No 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 GIF or progressive JPEG image.
Use this option to assign a specific label to the image. Optionally you can include the image filename, type, width, height, or scene number in the label by embedding special format characters. Embed %f for filename, %d for directory, %e for filename extention, %t for top of filename, %m for magick, %w for width, %h for height, %s for scene number, %b for file size in kilobytes, or \n for newline. For example,
-label "%m:%f %wx%h"
produces an image label of MIFF:bird.miff 512x480 for an image titled bird.miff and whose width is 512 and height is 480.
If the first character of string is @, the image label is read from a file titled by the remaining characters in the string.
When converting to Postscript, use this option to specify a header string to print above the image. Specify the label font with -font.
Use this option to extract a particular layer from the image. Matte, for example, is useful for extracting the opacity values from an image.
A value other than zero forces the animation to repeat itself up to iterations times.
By default, color reduction chooses an optimal set of colors that best represent the original image. Alternatively, you can choose a particular set of colors from an image file with this option. Use +map to reduce all images provided on the command line to a single optimal set of colors that best represent all the images.
Specify the percent change in brightness, the color saturation, and the color hue separated by commas. For example, to increase the color brightness by 20% and decrease the color saturation by 10% and leave the hue unchanged, use: -modulate 20/-10.
The red, green, and blue intensities of an image are negated. Use +negate to only negate the grayscale pixels of the 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 3 x 3 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 3 x 3 window.
Use +noise followed by a noise type to add noise to an image. Choose from these noise types:
uniform
gaussian
multiplicative
impulse
laplacian
poisson
This is a contrast enhancement technique.
Use this option to specify the dimensions of the Postscript page in dots per inch or a TEXT page in pixels. The choices for a Postscript page are:
Letter 612x 792
Tabloid 792x1224
Ledger 1224x 792
Legal 612x1008
Statement 396x 612
Executive 540x 720
A3 842x1190
A4 595x 842
A5 420x 595
B4 729x1032
B5 516x 729
Folio 612x 936
Quarto 610x 780
10x14 720x1008
For convenience you can specify the page size by media (e.g. A4, Ledger, etc.). Otherwise, -page behaves much like -geometry (e.g. -page letter+43+43>).
To position a GIF image, use -page {+-}<x offset>{+-}<y offset> (e.g. -page +100+200). For a Postscript page, the image is sized as in -geometry and positioned relative to the lower left hand corner of the page by {+-}<x offset>{+-}<y offset>. The default is to center the image within the page. If the image size exceeds the Postscript page, it is reduced to fit the page.
The default page dimensions for a TEXT image is 612x792.
This option is used in concert with -density.
Each pixel is replaced by the most frequent color in a circular neighborhood whose width is specified with radius.
See X(1) for details about the color specification.
For the JPEG image format, quality is 0 (worst) to 100 (best). The default quality is 75.
Quality for the MIFF and PNG image format sets the amount of image compression (quality / 10) and filter-type (quality % 10). Compression quality values range from 0 (worst) to 100 (best). If filter-type is 4 or less, the specified filter-type is used for all scanlines:
0: none
1: sub
2: up
3: average
4: Paeth
If filter-type is 5, adaptive filtering is used when quality is greater than 50 and the image does not have a color map, otherwise no filtering is used.
If filter-type is 6 or more, adaptive filtering with minimum-sum-of-absolute-values is used.
The default is quality is 75. Which means nearly the best compression with adaptive filtering.
For further information, see the PNG specification (RFC 2083), <http://www.w3.org/pub/WWW/TR>.
Use -raise to create a raised effect, otherwise use +raise.
By default, any command line options are applied to the entire image. Use -region to restrict operations to a particular area of the image.
A negative x offset rolls the image left-to-right. A negative y offset rolls the image top-to-bottom.
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 -90> and the image size is 480x640, the image is not rotated by the specified angle. However, if the image is 640x480, it is rotated by -90 degrees.
Empty triangles left over from rotating the image are filled with the color defined as bordercolor (class borderColor). See X(1) for details.
Specify cluster threshold as the number of pixels in each cluster must exceed the 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. See IMAGE SEGMENTATION for details.
Specify azimuth and elevation as the position of the light source. Use +shade to return the shading results as a grayscale image.
Shearing slides one edge of an image along the X or Y axis, creating a parallelogram. An X direction shear slides an edge along the X axis, while a Y direction shear slides an edge along the Y axis. The amount of the shear is controlled by a shear angle. For X direction shears, x degrees is measured relative to the Y axis, and similarly, for Y direction shears y degrees is measured relative to the X axis.
Empty triangles left over from shearing the image are filled with the color defined as bordercolor (class borderColor). See X(1) for details.
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 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
Finally, use this option to choose a particular resolution layer of a JBIG or JPEG image (e.g. -size 1024x768).
This option produces a solarization effect seen when exposing a photographic film to light during the development process.
Amount defines the size of the neighborhood around each pixel to choose a candidate pixel to swap.
Degrees defines the tightness of the swirl.
Create a bi-level image such that any pixel intensity that is equal or exceeds the threshold is reassigned the maximum intensity otherwise the minimum intensity.
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 quantize(9) for more details.
The -colors option is required for this option to take effect.
This option enables you to perform undercolor removal and black generation on CMYK images-- images to be printed on a four-color printing system. You can control how much cyan, magenta, and yellow to remove from your image and how much black to add to it. The standard undercolor removal is 1.0x1.0. You'll frequently get better results, though, if the percentage of black you add to your image is slightly higher than the percentage of C, M, and Y you remove from it. For example you might try 0.5x0.7.
This information is printed: image scene number; image name; converted 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.
Specify amplitude and wavelength to effect the characteristics of the wave.
Options are processed in command line order. Any option you specify on the command line remains in effect until it is explicitly changed by specifying the option again with a different effect. Some options only effect the decoding of images and others only the encoding.
By default, the image format is determined by its magic number. To specify a particular image format, precede the filename with an image format name and a colon (i.e. ps:image) or specify the image type as the filename suffix (i.e. image.ps). See DESCRIPTION for a list of valid formats.
When you specify X as your image type, the filename has special meaning. It specifies an X window by id, name, or root. If no filename is specified, the window is selected by clicking the mouse in the desired window.
Specify input_file as - for standard input, output_file as - for standard output. If input_file has the extension .Z or .gz, the file is uncompressed with uncompress or gunzip respectively. If output_file has the extension .Z or .gz, the file size is compressed using with compress or gzip respectively. Finally, precede the image file name with | to pipe to or from a system command.
Use an optional index enclosed in brackets after a file name to specify a desired subimage of a multi-resolution image format like Photo CD (e.g. img0001.pcd[4]) or a range for MPEG images (e.g. video.mpg[50-75]). A subimage specification can be disjoint (e.g. image.tiff[2,7,4]). For raw images, specify a subimage with a geometry (e.g. -size 640x512 image.rgb[320x256+50+50]).
Single images are written with the filename you specify. However, multi-part images (e.g. a multi-page Postscript document with +adjoin specified) are written with the filename followed by a period (.) and the scene number. You can change this behavior by embedding a printf format specification in the file name. For example,
image%02d.miff
converts files image00.miff, image01.miff, etc.
The % character is always interpreted in output filenames. To get a % character in the filename, use %%.
The fuzzy c-Means algorithm can be summarized as follows:
o Build a histogram, one for each color component of the image.
o For each histogram, successively apply the scale-space filter and build an interval tree of zero crossings in the second derivative at each scale. Analyze this scale-space ``fingerprint'' to determine which peaks or valleys in the histogram are most predominant.
o The fingerprint defines intervals on the axis of the histogram. Each interval contains either a minima or a maxima in the original signal. If each color component lies within the maxima interval, that pixel is considered ``classified'' and is assigned an unique class number.
o Any pixel that fails to be classified in the above thresholding pass is classified using the fuzzy c-Means technique. It is assigned to one of the classes discovered in the histogram analysis phase.
The fuzzy c-Means technique attempts to cluster a pixel by finding the local minima of the generalized within group sum of squared error objective function. A pixel is assigned to the closest class of which the fuzzy membership has a maximum value.
For additional information see
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