GIMP Unsharp Mask plug-in

The unsharp mask is the standard tool for sharpening images, especially photographs. It is less affected by noise than a standard sharpening filter and usually produces more natural-looking results. This plug-in is much faster than the script that is distributed with GIMP 1.0.0. It allows you to control the radius, amount, and threshold instead of just the radius, as the script does.