"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."
"For anyone who aspires to make good photos great, there's Paint Shop Pro X. You'll be able to learn as you go with a built-in Learning Center that lets you choose automatic photo fixes or precision editing controls for fine-tuning."