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.
Sketsa SVG Editor is a vector drawing application based on SVG. It allows users to create vector graphics that can be scaled and printed at any resolution, without losing detail or clarity. It features various tools for optimizing content creation, and includes a property palette, a DOM editor, a source editor, a resource editor, SVG-specific shape tools, transformation tools, and additional illustration tools. It uses SVG as its native file format.
Tux Paint is a simple and entertaining drawing program geared towards young children. It has a simple interface, sound effects, and a cartoon character (Tux, the Linux penguin). Along with drawing brush strokes, lines and shapes, you can also enter text and place "rubber stamp" (or "sticker") images on the picture. Tux Paint is extensible, and could be useful in an educational environment (such as a grammar, elementary, or grade school). It's portable across numerous platforms, and runs well even on slower systems like the Pentium 133MHz.
Evolvotron is an interactive "generative art" application to evolve images/textures/patterns through an iterative process of random mutation and user-selection driven evolution. If you like lava lamps, and never got tired of the Mandelbrot set, this could be the software for you. It's implemented using Qt, and is multithreaded.
Papyrus is a 2D C++ scenegraph (canvas) library that utilizes the cairo library to perform drawing operations. Similar canvas libraries are the Gnome Canvas, Diacanvas, and the QT Canvas. Numerous canvas primitives are available, including arcs, rectangles, polylines, and line markers. An optional companion library, Papyrusmm, provides a set of Gtkmm widgets which includes viewports (a canvas display widget similar to Gtk::DrawingArea) and other UI widgets related to drawing interfaces.
EZFB is a polymorphic, object oriented Linux frame buffer API written in C, designed to adapt at run time to control any properly configured Linux frame buffer video system. It offers independent, simultaneous control of multiple video cards within a single system, exceptional control of colors, the ability to display all or portions of bitmap files anywhere on the screen, automatic color depth conversion, the ability to capture to bitmap files, an 8x8 bitmapped font, routines to draw points, lines, outlined and filled rectangles, signal trapping for automatic screen clean-up at process termination, and much more. The demonstration applications include a bitmap viewer, screen capture utility, screen saver, and a touch screen calibration utility and an application for generating, viewing, transforming, and saving files according to The International Laser Display Association's ILDA file format.
Songwrite is a tablature editor. It supports many string instruments in addition to traditional staff notation. You can edit tablature (guitar, bass, banjo, etc.) and staff notation, add lyrics, create your own songbook, play your partitions, print your partitions and your songs, automatically convert staff notation to tablature and vice-versa, export songs to many formats (PDF, MIDI, ASCII tablature, GNU Lilypond, LaTeX, PostScript, etc.), and import Guitar Pro 3/4 files (experimental).
FrAid (Fr[actal] Aid) is a programming language that is appropriate for mathematical computations, visualization, batch processing, and more. It features both a standalone application that provides a programming environment for the language and a system for integrating the language with Java. The Java interface allows mathematical equations and formulas to be used with Java code, making it easier to process numerical computations, symbolic computations, imaging, CAD, and more.
Allegro Sprite Editor (ASE) is a program specially designed with facilities to create animated sprites that can be used in some video game. It lets you create static images, characters with movement, textures, patterns, backgrounds, logos, color palettes, etc. It focuses on pixel editing to do pixel art. It isn't a photo retouching tool or a vector graphics editor. Mainly, it is a tool to create tiny animations pixel-by-pixel.