webcam background blur effect

I've seen this effect before, where everything is blurred except the front most object in the shot. it was possibly a flash or flex effect which worked in realtime with video and snapshots. can anybody shed some light as to what this effect was called or point to some resources? thanks!

UPDATE: So it was the microsoft lifecam show which had this effect built in and can be seen here at the 2:11 mark: http://www.youtube.com/watch?v=u6ujUJU4Wqw

not as clean as i recall, but th开发者_高级运维at's what i'm looking for. Any ideas how this can be achieved in a custom app?

Apple makes a product like this called Photo Booth. It asks you to step out of the shot while it samples the background. You can apply filtered backdrops, or even video backdrops. When you step back into the picture, the backdrop appears behind you in realtime. It seems to do this by sampling the background color and using those colors to apply a mask to you when you step back in the shot. It's a pretty neat effect. Check it out http://www.apple.com/macosx/what-is-macosx/photo-booth.html.

There is an face-detection lib. You can handle each video frame blurring all except the face.