Image editor for advanced users

This is an extremely powerful digital image-editing program. By adding layers to an image, you can radically alter an image's original state. It also has a host of filters.

These will remove dust or scratches from a scanned image, sharpen or blur an area, and more. There are dozens more tools, too numerous to describe here.

GIMP has a steep learning curve and its manual is not deep. Advanced users might be happiest with it.Works on both Windows and Mac.