GIMP – The GNU Image Manipulation Program
If you are looking for some thing professional like Photoshop and having functions required by a professional and free than you are reading the exact information. GIMP is ideal for advanced photo retouching techniques. Get rid of unneeded details using the clone tool, or touch up minor details easily with the new healing tool. With the perspective clone tool, it’s not difficult to clone objects with perspective in mind just as easily as with the orthogonal clone.
GIMP is a versatile graphics manipulation package. This page should help you get a taste of what GIMP is capable of. You can also have a look at our introduction page or browse through the tutorials.
Paint.NET – Free Software for Digital Photo Editing
Paint.NET is free image and photo editing software for computers that run Windows. It features an intuitive and innovative user interface with support for layers, unlimited undo, special effects, and a wide variety of useful and powerful tools. An active and growing online community provides friendly help, tutorials, and plug-ins.
It started development as an undergraduate college senior design project mentored by Microsoft, and is currently being maintained by some of the alumni that originally worked on it.