You can do all that you were doing in PhotoShop , for free !! in GIMP :)

{GIMP} GNU Image Manipulation Program. It is a freely distributed piece of software suitable for such tasks as photo retouching, image composition and image authoring. 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, a image format converter, etc.

{click to see large size image}

To install the latest you just need to click :

http://cesium.di.uminho.pt/pub/getdeb/ubuntu/intrepid/gi/gimp_2.6.3-1~getdeb1_i386.deb