How to detect head in real time?

I want to detect heads (not faces) of multiple persons in a real time video (I'm using webcam) and count them. The head has to be detected even if it is tilted.

Answer 1

[Image Analyst]

Have you seen the demos where they do that: http://www.mathworks.com/products/computer-vision/features.html#object-tracking-and-motion-estimation