Creating icons

I’m working on a GraphicsMagick tool for making distro icons automatically. Seems like it might help, since designers can’t make icons individually for every distribution in the world. It’s going well so far. The biggest challenge I’ve had is color. I try to figure out what color an icon is to copy it, but they’re not solid colors, and have fuzzy edges. I was wondering what tool you all use to create your icons. Or maybe just how you define a color that is a mix of things (say, a color and transparent). Maybe that’ll will give me clue.