Patent ID: 8639026

Claim:
A background model learning system for lighting change adaptation for video surveillance comprising: a background model estimation circuit that estimates a background model B t for a scene of interest as its output of the current time instance t from at least one input of an image frame I t of the current time instance t; a foreground map construction circuit that constructs a reference foreground map F t of the time instance t that is a set of binary pixels denoting foreground and background pixel labels or a set of real-valued pixels denoting their possibilities of being foreground by background model subtraction between the image frame I t and the estimated background model B t ; and a lighting change processing circuit that revises the reference foreground map F t by reducing false foreground regions resulting from lighting changes, comprising: a frame differencing sub-circuit that generates a frame difference map D t of the time instance t via subtracting a previous image frame I t-N of the time instance t−N from the current one I t ; and a foreground map revising sub-circuit that computes a revised foreground map F t′ that has fewer regions of false foreground induced by lighting changes than the reference foreground map F t through integrating the frame difference map D t , the reference foreground map F t , and a feedback (revised foreground) map F t′-1 derived at the previous time instance t−1; wherein the revised foreground map F t′ acts as the output of the lighting change processing circuit at the current time instance t, and is then sent back to both the background model estimation circuit and the lighting change processing circuit as feedbacks for model learning rate tuning in background model estimation and map integration in lighting change processing, respectively, for the next time instance t+1, wherein the frame differencing sub-circuit for deriving the frame difference map D t in binary value of the current time instance t can be implemented by D t , x = { 1  I t , x - I t - N , x  > T d 0 otherwise , where D t,x εD t denotes a binary-valued pixel of the frame difference map D t at the pixel location x of the time instance t, I t,x denotes a pixel value of the image frame I t at the pixel location x of the time instance t, I t-N,x denotes a pixel value of the image frame I t-N at the pixel location x of the time instance t−N, and T d is a given threshold for binarizing the difference value; and the output of the frame differencing sub-circuit at the current time instance t is given by the frame difference map D t ={D t,x |∀x} denoting a set of binary-valued pixels D t,x s.