GraphicsMagick is a comprehensive image processing and 2D rendering system.
GraphicsMagick is a collection of tools and libraries which support reading, writing, and manipulating an image in many formats including TIFF, JPEG-2000, PNG, PDF, PhotoCD, JPEG, SVG, and GIF.
GraphicsMagick supports creating new images on the fly, making it suitable for building dynamic Web applications. GraphicsMagick may be used to resize, rotate, sharpen, color reduce, or add special effects to an image and save the result in the same or differing image format. Image processing operations are available from the command line, as well as through C, C++, Perl, or Windows COM programming interfaces. Extensions are available from third-parties to support programming in Borland's Delphi, Java, PHP, Python, Scheme, Tcl, and Ruby.
Command Line
gm - GraphicsMagick command-line utilities to create, edit, or convert images
Synopsis
gm animate [ options ... ] file [ [ options ... ] file ... ]
compare [ options ... ] reference-image [ options ... ] compare-image [ options ... ]
gm composite [ options ... ] change-image base-image [ mask-image ] output-image
gm conjure [ options ] script.msl [ [ options ] script.msl ]
gm convert [ [ options ... ] [ input-file ... ] [ options ... ] ] output-file
gm display [ options ... ] file ... [ [options ... ]file ... ]
gm identify file [ file ... ]
gm import [ options ... ] file
gm mogrify [ options ... ] file ...
gm montage [ options ... ] file [ [ options ... ] file ... ] output-file
Options
See GraphicsMagick GM Utility Options
gm mogrify
-modulate brightness[,saturation[,hue]] -gamma <value> level of gamma correction -level <black_point>{,<gamma>}{,<white_point>}{%} adjust the level of image contrast -contrast enhance or reduce the image contrast
To convert all the TIFF files in a particular directory to JPEG, use:
gm mogrify -format jpeg *.tiff
To convert a directory full of JPEG images to thumbnails, use:
gm mogrify -size 120x120 *.jpg -resize 120x120 +profile "*"
In this example, '-size 120x120' gives a hint to the JPEG decoder that the images are 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 images. 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 thumbnails.
To scale an image of a cockatoo to exactly 640 pixels in width and 480 pixels in height, use:
gm mogrify -resize 640x480! cockatoo.miff
gm mogrify -crop 1610x1610+358+85 DSCN0$No_D.JPG -quality 100
gm mogrify -operator all Noise-Gaussian '6.5%' file*.ppm
gm mogrify -modulate
gm mogrify -modulate 100,0 image.png
gm mogrify -gamma 2 -modulate 150,0 -quality 100 *
gm mogrify -gamma 2 -modulate 150,0 -quality 100 *