GIMP (GNU Image Manipulation Program) is a powerful photo and image editor for composition and authoring. It can be used as a simple paint program, a high quality photo retouching program, an online batch processing system, a mass production image renderer, an image format converter and much more.
The program is cross-platform with versions available for Mac and Linux. GIMP Portable is the PortableApps version of the program, and includes an available add-on that adjusts GIMP’s layout to mimic Photoshop and switched on single-window mode.
Alternatively, another portable package is X-Gimp.
