GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages. GIMP is very powerful with functionality not found in any other freeware product. It can be used as a simple paint program, an expert-quality photo-retoucher, mass production image renderer, or an image-format converter. GIMP is modular, expandable, and extensible.
Features:

• Scalable brushes.
• Improved selection tools.
• Full-screen editing.
• Improved Printing.
• Red Eye Removal. and much more…….

Customizable Interface

Each task requires a different environment and GIMP allows you to customize the view and behavior the way you like it. Starting from the widget theme, allowing you to change colors, widget spacings and icon sizes to custom tool sets in the toolbox. The interface is modulized into so called docks, allowing you to stack them into tabs or keep them open in their own window. Pressing the tab key will toggle them hidden.
GIMP features a great fullscreen mode allowing you to not only preview your artwork but also do editing work while using the most of your screen estate.

Photo Enhancement

Numerous digital photo imperfections can be easily compensated for using GIMP. Fix perspective distortion caused by lens tilt simply choosing the corrective mode in the transform tools. Eliminate lens’ barrel distortion and vignetting with a powerful filter but a simple interface.
The most visible changes in 2.7.3 are the fully working single-window mode, including working session management, and the introduction of a new hybrid spinbutton/scale widget which takes less space in dockable dialogs.
For a complete list of changes since 2.7.2 please refer to NEWS page, while the release notes summarize changes in the whole 2.7.x series.
Please note that the whole 2.7.x series of versions is considered unstable and is not recommended for use in production even though it might just work for you. Our intention is to make development versions available for passionate users who can provide useful feedback to help us fix bugs and streamline implementation of some of the new features. The upcoming v2.8 also introduces a huge amount of API deprecations and additions that have the potential to break existing 3rd party scripts and plug-ins. Please file bugs for all plug-ins and scripts that do work in v2.6, but don’t work in 2.7.3. A migration guide for developers will be provided when v2.8 is out.