GIMP originally known as the General Image Manipulation Program is an awesome open source alternative to such great apps as photoshop, you can do almost anything you could want to do with images with this program.  And as always it has the right price, you can download it and use it free and there is a great community for support if you need it.  With hundreds of plugins already available this is the photo editor you've dreamed of at the price anyone can afford. 

From GIMP:The "GNU Image Manipulation Program" (originally the General Image Manipulation Program) sired by Spencer Kimball & Peter Mattis.In their own words, "GIMP is our answer to the current lack of free (or at least reasonably priced) image manipulation software for GNU/Linux and UNIX in general."

It is a raster editor, which means that it performs operations directly on the pixels that make up the image, and not a vector editor. Other (proprietary) raster editors include Adobe Photoshop, Jasc Paintshop Pro and the humble Microsoft Paint. An alternative free editor is the KOffice project, Krita. Users wanting to edit photographs will certainly want a raster editor like GIMP. Graphic designers and illustrators may prefer a vector editor depending on their tastes. Click the blue arrow below to download GIMP.