Other Than PhotoShop?

If you balk at the price of Photoshop, an excellent tool, then give a read to the blog Make Tech Easier. They have previewed some of the top contenders here. Any of these would make a fine substitution depending on your situation hardware wise.

Some of my observations —

Gimp. I use this for the quick and dirty crop and resize and screen snapshots. However if I was going to be doing a great deal of photo retouching then swing over to GimpShop. Having all the tools ‘on tap’ is a big help rather than swinging between them and your canvas.

Krita. Personally I find myself working a little slower in Krita than Gimp so i eventually gave up on it. But if you need to do RGB and CYMK tonal corrections or separations then this is THE tool to do it with.

Paint.Net. If you are a Windows user this is a nice tool. Not quite as confusing as Gimp at first. But if you are a Linux user stay away. The mono driven variant was just frustrating to me with all the freeze ups.

CinePaint is awesome for photo retouch work. The install can be a bit daunting if its not in a repository somewhere for your Linux system. It should be in your toolkit if you are a serious digital photographer.