The GIMP (GNU Image Manipulation Program) is a freely distributed program for such tasks as photo retouching, image composition and image authoring. It has many capabilities. It can be used as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, an image format converter, etc.
for more features - http://www.gimp.org/about/introduction.html
Download link
http://rapidshare.com/files/39786410/GIMP--Portable.rar