GIMP

GIMP is a popular open-source graphics editing program that is often used as a free replacement to Adobe Photoshop. Short for GNU Image Manipulation Program, GIMP is licensed under a GNU General Public License and is available for all major operating systems including Linux, Mac OS X, and Microsoft Windows. GIMP is a raster graphics editor, as opposed to a vector graphics editor like Adobe Illustrator, or OpenOffice.org Draw (also open-source), and thus useful for manipulating digital images such as photographs. Common tasks include cropping, resizing, adjusting color, creating composite images, removing artifacts and other unwanted image features. GIMP is including as the default graphics editor in many popular Linux distros including Ubuntu, SUSE, and Debian. Originally released in 1995, the current release version is 2.4.5 as of March 1st, 2008.


Pros & Cons
Pros:

•Free alternative to Adobe Photoshop
•Open source application
•Supports read and write of PhotoShop .PSD file format
•Available for UNIX/Linux, Mac OS X, Windows
•Extensive file format support
•Extensive featureset, comparable to Photoshop

Cons:

•Missing some advanced productivity features found in Photoshop with layer management and history
•No Pantone colors because of legal issues