GIMP provides the tools needed for high quality image manipulation. From retouching to restoring to creative composites. GIMP provides top-notch color management features to ensure high-fidelity color reproduction across digital and printed media. It is best used in workflows involving other free software such as Scribus, Inkscape, and SwatchBooker.
GIMP provides a range of tutorials here
Free
GIMP is published under a GNU license. It is free to use.
