1. A computer-implementable method for classifying a detected region of change of a video frame as one of an abandoned object event and an object removal event, wherein a plurality of boundary blocks define a boundary of said region of change, said method comprising the steps of: (a) for each one of a set of said boundary blocks: (i) determining a predicted edge characteristic for said boundary block based on at least one edge characteristics of another boundary block adjacent to said boundary block; and (ii) determining an individual block score for said boundary block, based on said predicted edge characteristic for said boundary block and an observed edge characteristic for said boundary block; (b) determining a total score for said region of change, based on said individual block scores of said boundary blocks; and (c) classifying said region of change as said one of an abandoned object event and an object removal event based on said total score.