Patent ID: 7813528

Claim:
A method for detecting an object left-behind in a scene, comprising the steps of: updating a set of background models using a sequence of images acquired of a scene by a camera, each background model updated at temporal scales, wherein the temporal scales range from short term to long term; determining a foreground mask from each background model after the updating for a particular image of the sequence to produce a set of foreground masks; updating a motion image from the set of foreground masks, in which each pixel in the motion image has an associated evidence value, in which the set of foreground masks include a long-term mask F L and a short-term mask F S , and in which the updating of the motion image is according to evidence rules: if F L (x, y)=0 and F S (x, y)=0, then the pixel (x, y) corresponds to a background in the scene, and a corresponding pixel I(x, y) in a current image is represented in both the corresponding background models B L and B S ; if F L (x, y)=1 and F S (x, y)=1, then the pixel (x, y) corresponds to a moving object in the scene and is not represented in either of the background models B L or B S ; if F L (x, y)=0 and F S (x, y)=1, then the pixel (x, y) corresponds to scene background, and the pixel I(x, y) in the current image is only represented in the B L model; and if F L (x, y)=1 and F S (x, y)=0, then pixel (x, y) may correspond to the left-behind object, and in which the updating of the motion image M(x, y) is M ⁡ ( x , y ) = { M ⁡ ( x , y ) + 1 F L ⁡ ( x , y ) = 1 ⩓ F S ⁡ ( x , y ) = 0 M ⁡ ( x , y ) - k F L ⁡ ( x , y ) ≠ 1 ⩔ F S ⁡ ( x , y ) ≠ 0 max e M ⁡ ( x , y ) > max e 0 M ⁡ ( x , y ) < 0 , where a threshold max e and a delay constant k positive numbers; and comparing the evidence values with an evidence threshold to detect and signal an object left behind in the scene.