Ghostscript is a processor for PostScript and PDF files. It can rasterize these files to a wide variety of printers, devices for screen preview, and image file formats. Since applications tend to prepare pages for printing in a high-level format such as PostScript, most Unix users with low-level bitmap printers, such as inkjets, use GhostScript as part of the printing process. In addition, Ghostscript is capable of converting PostScript files, functionality comparable to Adobe Acrobat Distiller, but on the command line. In addition, Ghostscript is used for file import and viewing by a great many other applications, including xv, ImageMagick, gimp, and xdvi. Several GUI wrappers for viewing PostScript and PDF files exist, including GSview, ghostview, gv, ggv, and kghostview. This is far from a comprehensive list.
Gifsicle is a powerful command-line program for manipulating GIF image files. It has good support for transparency and colormap manipulation, simple image transformations (cropping, flipping), and creating, deconstructing, and editing GIF animations. It can also optimize GIF animations for space. Also included is a GIF animation viewer and a program that checks whether two GIFs look the same.
GraphicsMagick is a robust collection of tools and libraries which support reading, writing, and manipulating an image in over 90 major formats including popular formats like DPX, DICOM, BMP, GIF, JPEG, JPEG-2000, PDF, PNG, PNM, SVG, and TIFF. A high-quality 2D renderer is included, which provides a subset of SVG capabilities. C, C++, Perl, Tcl, and Ruby are supported. Originally based on ImageMagick, GraphicsMagick focuses on performance, minimizing bugs, and providing stable APIs and ABIs. It runs on all modern variants of Unix, Windows, and Mac OS X.
HPGL-Distiller filters out aspects of an HPGL file which are not relevant for various HPGL output devices, typically vinyl cutters. Irrelevant codes are filtered out to prevent many vinyl cutters from responding poorly to the excess data. With the use of HPGL-Distiller, you can use Inkscape, QCAD, GIMP, and many others to produce appropriate vinyl cutting output results.
HPGS is an HPGL/2 interpreter, which renders HPGL/2 and processes vector data through a Postscript-like API. It can render to EPS and PNG files. For rendering the scenery to pixel formats, it includes a rendering engine which draws vector graphics into pixel buffers. It also interprets inline PCL images.
ICCLIB implements support for reading and writing of color profile files that conform to the International Color Consortium (ICC) Profile Format Specification, Version 3.4. The ICC Profile Format is a cross-platform device profile format that can be used to translate color data created on one device into another device's native color space. See the profile specification at color.org. In summary ICCLIB provides support for all version 3.4 header elements, Tags, and Tag Types, conversion to/from machine native representation of all data types, user-defined Tags, adding/deleting Tags, Tag type sharing within a file (often used for sharing LUTs amongst intents), reading/writing embedded profiles, a single function for transforming color values through a profile (including support for intents, forward and reverse transforms, gamut lookup or preview lookup), support and code examples for creating all profile types, monochrome, matrix, and Lut, and it loads Tag Types on demand to conserve memory space.
Ilib is an image manipulation library for developers. It's capable of reading and writing images (PPM/PGM, PNG, JPEG, GIF, XPM, BMP) and many drawing functions including drawing lines and text using any BDF (X11) font. It's great for generating GIFs/PNGs from a CGI or generating graphs. Ilib includes sample applications for generating graphs for HTTP access.log files and QuakeWorld server frag log files and a tool for creating image indices from a group of images.
Image Alchemy has the ability to convert between over 90 different raster image formats (including all colorspace and compression variations of each format). Color management features include gamma correction, undercolour removal, seven high quality dithers, colorspace conversion, and palette manipulation. It also includes a Postscript interpreter.