1. A computer implemented method of object extraction from video images, the method comprising steps a computer is programmed to perform, the steps comprising: receiving a plurality of video images; deriving a plurality of background templates from at least one of the received video images; calculating a plurality of differences from an individual one of the received video images, each one of the differences being calculated between the individual video image and a respective and different one of the background templates; and extracting an object of interest from the individual video image, using a rule applied on the calculated differences.