An Open Source Application was recommened by 3D world magazine as to a solution to paying for Photoshop. Its called The Gimp.

Heres a link:

https://gimp-win.sourceforge.net/stable.html

Supposed to be very good. Not used it personally, but it was used on the Open Source Animated Short called Elephants Dream. Yes, it was made with entirely free software...

I would recommend a viewing just to see what can be done with entirely free software.