Some of my students are working on a project where they need a photo-booth-like keying application (take snapshot with somebody out of the picture, then step back in the picture and the background disappears). I’ve been experimenting with pixelbender the last week, and created some classes that do just that.
Check out the example, and play around with the parameters. Please note that it works best with a background without too much detail or similarities with the person in front. Also make sure there’s enough lighting.
You can download the source files and play around with them.