Patent ID: 7181050

Claim:
A method of detecting a facial region within a video comprising the steps of: (a) receiving a first frame of said video comprising a plurality of pixels; (b) receiving a subsequent frame of said video comprising a plurality of pixels; (c) calculating a difference image representative of the difference between a plurality of said pixels of said first frame and a plurality of said pixels of said subsequent frame; (d) determining a plurality of candidate facial regions within said difference image based on a Hough transform of said difference image in a spatial domain to a parameter space of the form A ( x c , y c , r )= A ( x c , y c , r )+1 ∀x c , y c , r ε( x−x c ) 2 +( y−y c ) 2 =r 2 ; and (e) fitting said plurality of candidate facial regions to said difference image, where said difference image used for said fitting is free from being transformed as a result of step (d), to select one of said candidate facial regions.