The volunteer developers of The GIMP have been working hard to develop a polished, user-friendly, and freely distributed image editor. Available for Windows and Mac users, and in a portable edition for the PC, the separated palette windows may disturb those users who are used to more traditional layouts. Still, your comfort level should grow exponentially as you discover how pain-free the program is.
One of the most powerful general-purpose image editors around, the GNU Image Manipulation Program is eminently comparable to Photoshop. Older features include channels, layers and masks, filters and effects, tabbed palettes, editable text tools, and color operations such as levels. New improvements include scalable brushes, revised selection tools, a new color menu, full-screen editing, a new crop tool, improved printing, red-eye removal, perspective clone, lens distortion, and more. It even has regex-based pattern matching for power users.
Extremely powerful and easy to work with, GIMP is ideal for both amateur and pro photographers, Web designers, or anyone who wants to create and edit professional-quality digital images on a budget.