Graphics Tools
ImageMagick
- Powerful interactive image manipulation, viewing and animation tool. Will convert, resize, thumbnail, create transparent, create composite & much more
GNU Image Manipulation Program
- The GIMP, styled loosely after Adobe Photoshop, can be used for photo retouching, image composition and image authoring
XV
- This shareware image viewer/manipulator has an excellent user interface and image enhancing algorithms. Widely used and respected tool.