This is an old revision of the document!
Here is a guide to using GIMP for doing some of the more common kinds of things you would need to do when editing images for use in games.
GIMP may or may not be the best tool for doing this. But it's open source (something that's important to me), it's available for all major desktop operating systems, I know it, and it works.
In what follows, I am assuming you are using PNG images for all your image resources. With small changes, everything should apply to other formats as well.
You've got two choices if you are going to use GIMP on Windows: you can install it as a regular program or you can use the portable version
myImage.png(Make sure the extension is
Often times an image will have extra borders or padding around it that you won't want. (It will make sprites larger than they need to be–which will affect collisions and other things.