c# face recognition

I can suggest to use emgucv, as it comes with an example that works on vs2010 and show you how to do face detection. once you have detected your face you can easily crop your detected face, setting ROI properly.

That's called computer vision. There's a popular library that supports those types of op's. I wouldn't call it easy, but do-able...

http://www.aforgenet.com/framework/

Probably i think this is what you need http://ashishrd.blogspot.com/2006/12/gesture-recognition-using-webcam-and.html gesture detector and Artificially call up an event while sensor square is touch