GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software suitable for such tasks as photo retouching, image composition and image authoring. It can be used as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, a image format converter, etc.
Asymptote is a powerful descriptive 2D and 3D vector graphics language for technical drawing, inspired by MetaPost but with an improved C++-like syntax. It provides for figures the same high-quality level of typesetting that LaTeX does for scientific text. Asymptote is a programming language as opposed to just a graphics program. It can exploit the best features of script (command-driven) and graphical user interface (GUI) methods. High-level graphics commands are implemented in the language itself, allowing them to be easily tailored to specific applications.
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.
Inkscape is a drawing tool with capabilities similar to Illustrator, Freehand, and CorelDraw that uses the W3C standard scalable vector graphics format (SVG). The supported SVG features include basic shapes, paths, text, markers, clones, alpha blending, transforms, gradients, and grouping. In addition, it supports Creative Commons meta-data, node-editing, layers, complex path operations, text-on-path, and SVG XML editing. It also imports several formats like EPS, Postscript, JPEG, PNG, BMP, and TIFF and exports PNG as well as multiple vector-based formats.
Audacity is a cross-platform multitrack audio editor. It allows you to record sounds directly or to import Ogg, WAV, AIFF, AU, IRCAM, or MP3 files. It features a few simple effects, all of the editing features you should need, and unlimited undo. The audio I/O uses PortAudio, which fully supports OSS, Mac OS X CoreAudio, and Windows WMME, and can be compiled with support for ALSA and Jack.
white_dune is a graphical VRML97/X3DV editor, simple NURBS/Superformula 3D modeller, animation tool, and VRML97/X3DV commandline compiler in development. VRML97 (Virtual Reality Modeling Language) is the ISO standard for displaying 3D data over the Web via browser plugins ("HTML for realtime 3D"). X3DV is the direct successor of VRML97. VRML97 and X3DV have support for animation, real-time interaction, and multimedia (images, movies, and sounds). white_dune can read, create, and display VRML97/X3DV files and let the user change the scenegraph/fields. It also has support for stereoscopic view via "quadbuffer"-capable stereo visuals, and support for 3D input devices like a joystick, spaceball, or magnetic tracker.
Ecasound is a software package designed for multitrack audio processing. It can be used for simple tasks like audio playback, recording, and format conversions, as well as for multitrack effect processing, mixing, recording and signal recycling. It supports a wide range of audio inputs, outputs, and effect algorithms. Effects and audio objects can be combined in various ways, and their parameters can be controlled by operator objects like oscillators and MIDI-CCs. A versatile console-mode user interface is included in the package.