convert recognizes the following image formats:
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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 595x842+0+0 image.tiff document.ps
To convert a raw GRAY image to a portable graymap, use:
convert -geometry 768x512 gray:raw image.pgm
Use clipping to crop a particular area of an image. Use -clip 0x0 to remove edges that are the background color.
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 remain unchanged. 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 -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, %m for magick, %w for width, %h for height, %s for scene number, 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 specifies an image density for a Postscript page. The default is 72 dots per inch in the horizontal and vertical direction. Use this option to alter the default density.
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.
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 commas (i.e. 1.7,2.3,1.2).
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 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 -geometry to tell the number of colors in a MAP image file, (e.g. -geometry 640x512+256).
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...).
The red, green, and blue intensities of an image are negated.
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, %m for magick, %w for width, %h for height, or %s for scene number. 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.
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.
This is a contrast enhancement technique.
Use this option to specify the dimensions of the Postscript page in picas or a TEXT page in pixels. The default for a Postscript page is to center the image on a letter page 612 by 792 dots per inch. The left and right margins are 18 picas and the top and bottom 94 picas (i.e. 612x792+18+94). Other common sizes are:
540x720 Note
612x1008 Legal
842x1190 A3
595x842 A4
421x595 A5
297x421 A6
709x1002 B4
612x936 U.S. Foolscap
612x936 European Foolscap
396x612 Half Letter
792x1224 11x17
1224x792 Ledger
The page geometry is relative to the vertical and horizontal density of the Postscript page. See -density for details.
The default page dimensions for a TEXT image is 612x792+36+36.
Quality is 0 (worst) to 100 (best). The default is 85.
Empty triangles left over from rotating the image are filled with the color defined by the pixel at location (0,0). Refer to -border to choose a specific color.
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 by the pixel at location (0,0). Refer to -border to choose a specific color.
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 convert the image.
Change '-' to '+' in any option above to reverse its effect. For example, specify +alpha to store the image without its alpha channel.
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. If output_file already exists, you will be prompted as to whether it should be overwritten.
Single images are written with the filename you specify. However, multi-part images (i.e. a multi-page Postscript document) 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.miffconverts files image00.miff, image01.miff, etc.
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E. I. du Pont de Nemours & Company disclaims all warranties with regard to this software, including all implied warranties of merchantability and fitness, in no event shall E. I. du Pont de Nemours & Company be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortuous action, arising out of or in connection with the use or performance of this software.