title: How does an unsharp mask work?
body: <p>I've been playing around with image processing lately, and I'd like to know how the unsharp mask algorithm works.  I'm looking at the source code for Gimp and it's implementation, but so far I'm still in the dark about how it actually works.  I need to implement it for a project I'm working on, but I'd like to actually understand the algorithm I'm using.</p>