convert(1) ImageMagick convert(1) 19 Feb 1995
NAME convert - converts an input file using one image format to an output file with a differing image format.
SYNOPSIS convert [ options ... ] input_file output_file
DESCRIPTION convert converts an input file using one image format to an output file with a differing image format.
convert recognizes the following image formats:
Tag Description
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AVS AVS X image file.
BIE+ Joint Bi-level Image experts Group file interchange format.
BMP+ Microsoft Windows bitmap image file.
CMYK Raw cyan, magenta, yellow, and black bytes.
DCX+ ZSoft IBM PC multi-page Paintbrush file.
DIB Microsoft Windows bitmap image file.
EPS Adobe Encapsulated PostScript file.
EPS2 Adobe Level II Encapsulated PostScript file.
EPSF Adobe Encapsulated PostScript file.
EPSI Adobe Encapsulated PostScript Interchange format.
FAX+ Group 3.
FITS Flexible Image Transport System.
GIF+ Compuserve Graphics image file.
GIF87+ Compuserve Graphics image file (version 87a).
GRAY Raw gray bytes.
HDF+ Hierarchical Data Format.
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HTML Hypertext Markup Language.
HISTOGRAM
JBIG+ Joint Bi-level Image experts Group file interchange format.
JPEG Joint Photographic Experts Group file interchange format.
MAP Red, green, and blue colormap bytes followed by the image colormap indexes.
MATTE Raw matte bytes.
MIFF+ Magick image file format.
MPEG+ Motion Picture Experts Group file interchange format.
MTV+ MTV Raytracing image format.
NULL NULL image.
PCD Photo CD.
PCX ZSoft IBM PC Paintbrush file.
PDF+ Portable Document Format.
PICT Apple Macintosh QuickDraw/PICT file.
PNG Portable Network Graphics.
PNM+ Portable bitmap.
PS+ Adobe PostScript file.
PS2+ Adobe Level II PostScript file.
RAD Radiance image format.
RGB Raw red, green, and blue bytes.
RGBA Raw red, green, blue and matte bytes.
RLA Alias/Wavefront image file; read only
RLE Utah Run length encoded image file; read only.
SGI+ Irix RGB image file.
SUN+ SUN Rasterfile.
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TEXT raw text file; read only.
TGA+ Truevision Targa image file.
TIFF+ Tagged Image File Format.
TILE tile image with a texture.
UYVY 16bit/pixel interleaved YUV (e.g. used by AccomWSD).
VICAR read only.
VID Visual Image Directory.
VIFF+ Khoros Visualization image file.
X select image from X server screen.
XC constant image of X server color. Specify the desired color as the filename.
XBM X11 bitmap file.
XPM X11 pixmap file.
XWD X Window System window dump image file.
YUV CCIR 601 4:1:1 file.
YUV3 CCIR-601 4:1:1 files.
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.
EXAMPLES 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:
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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 12x24 -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 -page +50+100 dna.* dna.gif
OPTIONS -adjoin join images into a single multi-image file.
-blur factor blurs an image. Specify factor as the percent enhancement (0.0 - 99.9%).
-border <width>x<height> surround the image with a border or color. See X(1) for details about the geometry specification.
The color of the border is specified with the -bordercolor command line option.
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-box color set the color of the annotation bounding box. See -draw or for further details.
See X(1) for details about the color specification.
-colors value 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, 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.
-colorspace value the type of colorspace: GRAY, OHTA, RGB, Transparent, XYZ, YCbCr, YIQ, YPbPr, or YUV.
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 perserves the matte channel of the image if it exists.
The -colors or -monochrome option is required for this option to take effect.
-comment string annotate an image with a comment.
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, %b for file size in kilobytes, 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
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from a file titled by the remaining characters in the string.
-compress type the type of image compression: Zip or RunlengthEncoded.
Specify +compress to store the binary image in an uncompressed format. The default is the compression type of the specified image file.
-contrast 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.
-crop <width>{%}x<height>{%}{+-}<x offset>{+-}<y offset> preferred size and location of the cropped image. See X(1) for details about the geometry specification.
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.
-delay <1/100ths of a second> display the next image after pausing.
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.
-density <width>x<height> vertical and horizontal resolution in pixels of the image.
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.
-despeckle reduce the speckles within an image.
-display host:display[.screen] specifies the X server to contact; see X(1).
-dither apply Floyd/Steinberg error diffusion to the image.
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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.
-draw string annotate an image with one or more graphic primitives.
Use this option to annotate an image with one or more graphic primitives. The primitives include
rectangle circle polygon text image
Rectangle, text, and image require an upper left and lower right coordinate. Circle requires the 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'
If the first character of string is @, the text is read from a file titled by the remaining characters in the string.
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, %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,
-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.
If the first character of the string is @, the text is read from a file titled by the remaining characters in the string.
Use image to composite an image with another image. Follow the image coordinates with the filename of an image.
You can set the primitive color, font color, and font bounding
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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.
-edge factor detect edges with an image. Specify factor as the percent enhancement (0.0 - 99.9%).
-emboss emboss the image.
-enhance apply a digital filter to enhance a noisy image.
-equalize perform histogram equalization to the image.
-flip create a "mirror image" by reflecting the image scanlines in the vertical direction.
-flop create a "mirror image" by reflecting the image scanlines in the horizontal direction.
-font name use this font when annotating the image with text.
Convert contacts an X server to obtain the font. If an X server is not available, a Postscript font is used. You can set the pointsize with -pointsize.
-frame <width>x<height>+<outer bevel width>+<inner bevel width> surround the image with an an ornamental border. See X(1) for details about the geometry specification.
The color of the border is specified with the -mattecolor command line option.
-gamma value 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.
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).
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-geometry <width>{%}x<height>{%}{!}{<}{>} preferred size or location of the image when encoding.
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.
-implode amount implode image pixels about the center.
Amount defines the force of the implosion. A negative amount forces an explosion rather than implosion. Reasonable values range from -10 to 1.0.
-interlace type the type of interlacing scheme: NONE, LINE, or PLANE.
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...).
Use LINE, or PLANE to create an interlaced GIF or progressive JPEG image. -label name assign a label to an 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, %m for magick, %w for width, %h for height, %s for scene number, %b for file size in
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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.
-loop iterations add Netscape loop extension to your GIF animation.
A value other than zero forces the animation to repeat itself up to iterations times.
-map filename choose a particular set of colors from this image.
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 with this option.
-matte store matte channel if the image has one.
-modulate value vary the brightness, saturation, and hue of an image.
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.
-monochrome transform the image to black and white.
-negate apply color inversion to image.
The red, green, and blue intensities of an image are negated.
-noise reduce the noise in an image with a noise peak elimination filter.
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
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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.
-normalize transform image to span the full range of color values.
This is a contrast enhancement technique.
-opaque color change this color to the pen color within the image. See -pen for more details.
-page <width>x<height>{+-}<x offset>{+-}<y offset> preferred size and location of the Postscript page.
Use this option to specify the dimensions of the Postscript page in pixels per inch or a TEXT page in pixels. The default for a Postscript page is to center the image on a letter page 612 by 792 pixels. The margins are 1/2" (i.e. 612x792+42+42). Other common sizes 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.).
To place a Postscript image with a given size on a given location on a page, use -page +HOFFSET+VOFFSET -geometry WIDTHxHEIGHT (fill in numbers). Note: this is only for generating Postscript, not Encapsulated Postscript.
To position a GIF image, use -page +LEFT+TOP (e.g. -page +100+200).
The default page dimensions for a TEXT image is 612x792.
-paint paint the image.
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-pen color set the color of the font or opaque color. See -draw or -opaque for further details.
See X(1) for details about the color specification.
-pointsize value pointsize of the Postscript font.
-quality value JPEG quality setting.
Quality is 0 (worst) to 100 (best). The default is 75.
-raise <bevel width> lighten or darken image edges to create a 3-D effect.
Bevel width is the width of an edge. Use -raise to create a raised effect, otherwise use +raise.
-roll {+-}<x offset>{+-}<y offset> roll an image vertically or horizontally. See X(1) for details about the geometry specification.
A negative x offset rolls the image left-to-right. A negative y offset rolls the image top-to-bottom.
-rotate degrees apply Paeth image rotation to the image.
Empty triangles left over from rotating the image are filled with the color defined as bordercolor (class borderColor). See X(1) for details.
-sample geometry scale image with pixel sampling.
-scene value image scene number.
-segment value eliminate clusters that are insignificant.
The number of pixels in each cluster must exceed the the cluster threshold to be considered valid. See IMAGE SEGMENTATION for details.
-sharpen factor sharpen an image. Specify factor as the percent enhancement (0.0 - 99.9%).
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-shear <x degrees>x<y degrees> shear the image along the X or Y axis by a positive or negative shear angle.
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.
-size <width>{%}x<height>{%}+<offset> 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 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 image (e.g. -size 1024x768).
-spread amount displace image pixels by a random amount.
Amount defines the size of the neighborhood around each pixel to choose a candidate pixel to swap.
-swirl degrees swirl image pixels about the center.
Degrees defines the tightness of the swirl.
-texture filename name of texture to tile onto the image background.
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-transparency color make this color transparent within the image.
-treedepth value Normally, this integer value is zero or one. A zero or one tells convert to choose a 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 quantize(9) for more details.
The -colors option is required for this option to take effect.
-undercolor <undercolor factor>x<black-generation factor> control undercolor removal and black generation on CMYK images.
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.
-verbose print detailed information about the image.
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.
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.
Change '-' to '+' in any option above to reverse its effect. For example, specify +matte to store the image without its matte 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.
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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]).
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.
IMAGE SEGMENTATION Use -segment to segment an image by analyzing the histograms of the color components and identifying units that are homogeneous with the fuzzy c-means technique. The scale-space filter analyzes the histograms of the three color components of the image and identifies a set of classes. The extents of each class is used to coarsely segment the image with thresholding. The color associated with each class is determined by the mean color of all pixels within the extents of a particular class. Finally, any unclassified pixels are assigned to the closest class with the fuzzy c-means technique.
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
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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
Young Won Lim, Sang Uk Lee, "On The Color Image Segmentation Algorithm Based on the Thresholding and the Fuzzy c-Means Techniques", Pattern Recognition, Volume 23, Number 9, pages 935-952, 1990.
ENVIRONMENT DISPLAY To get the default host, display number, and screen.
SEE ALSO display(1), animate(1), import(1), montage(1), mogrify(1), combine(1), xtp(1)
COPYRIGHT Copyright 1996 E. I. du Pont de Nemours and Company
Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of E. I. du Pont de Nemours and Company not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. E. I. du Pont de Nemours and Company makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.
E. I. du Pont de Nemours and 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 and 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.
AUTHORS John Cristy, E.I. du Pont De Nemours and Company Incorporated
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