gm convert
NAME
| convert - convert an image or sequence of images
Contents
| Synopsis Description Examples Options Image Segmentation Environment Configuration Files Authors Copyright
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. In addition, various types of image processing can be performed on the converted image during the conversion process. Convert recognizes the image formats listed in GraphicsMagick(1).
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Examples
| To make a thumbnail of a JPEG image, use:
        gm convert -size 120x120 cockatoo.jpg -resize 120x120 +profile "*" thumbnail.jpg
| In this example, `'-size 120x120'` gives a hint to the JPEG decoder that the image is going to be downscaled to 120x120, allowing it to run faster by avoiding returning full-resolution images to GraphicsMagick for the subsequent resizing operation. The `'-resize 120x120'` specifies the desired dimensions of the output image. It will be scaled so its largest dimension is 120 pixels. The `'+profile "*"'` removes any ICM, EXIF, IPTC, or other profiles that might be present in the input and aren't needed in the thumbnail.
To convert a MIFF image of a cockatoo to a SUN raster image, use:
        gm convert cockatoo.miff sun:cockatoo.ras
To convert a multi-page PostScript document to individual FAX pages, use:
        gm 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:
        gm 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:
        gm convert -depth 8 -size 768x512+128 gray:raw image.pgm
In this example, "raw" is the input file. Its format is "gray" and it has the dimensions and number of header bytes specified by the -size option and the sample depth specified by the -depth option. The output file is "image.pgm". The suffix ".pgm" specifies its format. To convert a Photo CD image to a TIFF image, use:
        gm convert -size 1536x1024 img0009.pcd image.tiff
        gm convert img0009.pcd[4] image.tiff
To create a visual image directory of all your JPEG images, use:
        gm convert 'vid:*.jpg' directory.miff
To annotate an image with blue text using font 12x24 at position (100,100), use:
        gm convert -font helvetica -fill blue -draw "text 100,100 Cockatoo"
                bird.jpg bird.miff
To tile a 640x480 image with a JPEG texture with bumps use:
        gm convert -size 640x480 tile:bumps.jpg tiled.png
To surround an icon with an ornamental border to use with Mosaic(1), use:
        gm convert -mattecolor "#697B8F" -frame 6x6 bird.jpg icon.png
To create a MNG animation from a DNA molecule sequence, use:
        gm convert -delay 20 dna.* dna.mng
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Options
| Options are processed in command line order. Any option you specify on the command line remains in effect for the set of images that follows, until the set is terminated by the appearance of any option or -noop. Some options only affect the decoding of images and others only the encoding. The latter can appear after the final group of input images. For a more detailed description of each option, see Options, above. GraphicsMagick(1). For a more detailed description of each option, see Options, above. GraphicsMagick(1).
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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: Build a histogram, one for each color component of the image. 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. 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. 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: 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.
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Environment
| COLUMNS
| Output screen width. Used when formatting text for the screen. Many Unix systems keep this shell variable up to date, but it may need to be explicitly exported in order for GraphicsMagick to see it.
| DISPLAY
| X11 display ID (host, display number, and screen in the form hostname:display.screen).
| HOME
| Location of user's home directory. GraphicsMagick searches for configuration files in $HOME/.magick if the directory exists. See MAGICK_CODER_MODULE_PATH, MAGICK_CONFIGURE_PATH, and MAGICK_FILTER_MODULE_PATH if more flexibility is needed.
| MAGICK_CODER_STABILITY
| The minimum coder stability level before it will be used. The available levels are PRIMARY, STABLE, and UNSTABLE. The default minimum level is UNSTABLE, which means that all available coders will be used. The purpose of this option is to reduce the security exposure (or apparent complexity) due to the huge number of formats supported. Coders at the PRIMARY level are commonly used formats with very well maintained implementations. Coders at the STABLE level are reasonably well maintained but represent less used formats. Coders at the UNSTABLE level either have weak implementations, the file format itself is weak, or the probability the coder will be needed is vanishingly small.
| MAGICK_CODER_MODULE_PATH
| Search path to use when searching for image format coder modules. This path allows the user to arbitrarily extend the image formats supported by GraphicsMagick by adding loadable modules to an arbitrary location rather than copying them into the GraphicsMagick installation directory. The formatting of the search path is similar to operating system search paths (i.e. colon delimited for Unix, and semi-colon delimited for Microsoft Windows). This user specified search path is used before trying the default search path.
| MAGICK_CONFIGURE_PATH
| Search path to use when searching for configuration (.mgk) files. The formatting of the search path is similar to operating system search paths (i.e. colon delimited for Unix, and semi-colon delimited for Microsoft Windows). This user specified search path is used before trying the default search path.
| MAGICK_DEBUG
| Debug options (see -debug for details)
| MAGICK_FILTER_MODULE_PATH
| Search path to use when searching for filter process modules (invoked via -process). This path allows the user to arbitrarily extend GraphicsMagick's image processing functionality by adding loadable modules to an arbitrary location rather than copying them into the GraphicsMagick installation directory. The formatting of the search path is similar to operating system search paths (i.e. colon delimited for Unix, and semi-colon delimited for Microsoft Windows). This user specified search path is used before trying the default search path.
| MAGICK_HOME
| Path to top of GraphicsMagick installation directory. Only observed by "uninstalled" builds of GraphicsMagick which do not have their location hard-coded or set by an installer.
| MAGICK_MMAP_READ
| If MAGICK_MMAP_READ is set to TRUE, GraphicsMagick will attempt to memory-map the input file for reading. This usually substantially improves read performance if the file has recently been read. However, testing shows that performance may be reduced for files accessed for the first time via a network since some operating systems failed to do read-ahead over network mounts for memory mapped files.
| MAGICK_MMAP_WRITE
| If MAGICK_MMAP_WRITE is set to TRUE, GraphicsMagick will attempt to memory-map the output file for writing. This is an experimental feature (which is currently broken). Write performance is usually somewhat worse when using this approach rather than the default one.
| MAGICK_IO_FSYNC
| If MAGICK_IO_FSYNC is set to TRUE, then GraphicsMagick will request that the output file is fully flushed and synchronized to disk when it is closed. This incurs a performance penalty, but has the benefit that if the power fails or the system crashes, the file should be valid on disk. If image files are referenced from a database, then this option helps assure that the files referenced by the database are valid.
| MAGICK_IOBUF_SIZE
| The amount of I/O buffering (in bytes) to use when reading and writing encoded files. The default is 16384, which is observed to work well for many cases. The best value for a local filesystem is usually the the native filesystem block size (e.g. 4096, 8192, or even 131,072 for ZFS) in order to minimize the number of physical disk I/O operations. I/O performance to files accessed over a network may benefit significantly by tuning this option. Larger values are not necessarily better (they may be slower!), and there is rarely any benefit from using values larger than 32768. Use convert's -verbose option in order to evaluate read and write rates in pixels per second while keeping in mind that the operating system will try to cache files in RAM.
| MAGICK_LIMIT_DISK
| Maximum amount of disk space allowed for use by the pixel cache.
| MAGICK_LIMIT_FILES
| Maximum number of open files.
| MAGICK_LIMIT_MAP
| Maximum size of a memory map.
| MAGICK_LIMIT_MEMORY
| Maximum amount of memory to allocate from the heap.
| MAGICK_TMPDIR
| Path to directory where GraphicsMagick should write temporary files. The default is to use the system default, or the location set by TMPDIR.
| TMPDIR
| For POSIX-compatible systems (Unix-compatible), the path to the directory where all applications should write temporary files. Overridden by MAGICK_TMPDIR if it is set.
| TMP or TEMP
| For Microsoft Windows, the path to the directory where applications should write temporary files. Overridden by MAGICK_TMPDIR if it is set.
| OMP_NUM_THREADS
| As per the OpenMP standard, this specifies the number of threads to use in parallel regions. Some compilers default the number of threads to use to the number of processor cores available while others default to just one thread. See the OpenMP specification for other standard adjustments and your compiler's manual for vendor-specific settings.
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Configuration Files
| GraphicsMagick uses a number of XML format configuration files:
| colors.mgk
| colors configuration file
      <?xml version="1.0"?>
      <colormap>
        <color name="AliceBlue" red="240" green="248" blue="255"
               compliance="SVG, X11, XPM" />
      </colormap>
| delegates.mgk
| delegates configuration file
| log.mgk
| logging configuration file
      <?xml version="1.0"?>
      <magicklog>
        <log events="None" />
        <log output="stdout" />
        <log filename="Magick-%d.log" />
        <log generations="3" />
        <log limit="2000" />
        <log format="%t %r %u %p %m/%f/%l/%d:\n  %e"  />
      </magicklog>
| modules.mgk
| loadable modules configuration file
      <?xml version="1.0"?>
      <modulemap>
        <module magick="8BIM" name="META" />
      </modulemap>
| type.mgk
| master type (fonts) configuration file
      <?xml version="1.0"?>
      <typemap>
        <include file="type-windows.mgk" />
        <type
          name="AvantGarde-Book"
          fullname="AvantGarde Book"
          family="AvantGarde"
          foundry="URW"
          weight="400"
          style="normal"
          stretch="normal"
          format="type1"
          metrics="/usr/local/share/ghostscript/fonts/a010013l.afm"
          glyphs="/usr/local/share/ghostscript/fonts/a010013l.pfb"
        />
      </typemap>
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Authors
| John Cristy, Bob Friesenhahn, Glenn Randers-Pehrson, William Radcliff, Leonard Rosenthol.
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Copyright
| Copyright (C) 2002 - 2010 GraphicsMagick Group, an organization dedicated to making software imaging solutions freely available. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files ("GraphicsMagick"), to deal in GraphicsMagick without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of GraphicsMagick, and to permit persons to whom GraphicsMagick is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of GraphicsMagick. The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall GraphicsMagick Group be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with GraphicsMagick or the use or other dealings in GraphicsMagick. Except as contained in this notice, the name of the GraphicsMagick Group shall not be used in advertising or otherwise to promote the sale, use or other dealings in GraphicsMagick without prior written authorization from the GraphicsMagick Group. Additional copyrights and licenses apply to this software. You should have received a copy of Copyright.txt with this package, which describes additional copyrights and licenses which apply to this software; otherwise see http://www.graphicsmagick.org/Copyright.html.
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