(
GNU
Image
Manipulation
Program) An open source paint and image editing program for Unix, Linux, Mac and Windows that originated as an undergraduate project by Peter Mattis and Spencer Kimball at the University of California, Berkeley. Numerous programmers have contributed to the project, turning GIMP into a serious image manipulation tool that supports layers, alpha channels, third-party plug-ins and three scripting languages.
Full Featured
Using Python, Perl or Script-Fu scripts, GIMP can be used for batch processing and the automation of tasks such as the interpolation of frames for animation sequences. The GIMP source code is distributed under the GNU General Public License (GPL). "Grokking the GIMP" by Carey Bunks is a comprehensive manual for GIMP users.
GIMP In Action
GIMP provides sophisticated paint and editing functions as is evident in these various dialogs and palettes. (Image courtesy of Carey Bunks.)