1. A method for detecting motion in sequential images, said method comprising the steps of: defining a target size parameter indicating a minimized area to trigger an alarm, defining a global change parameter, creating a reference frame in dependence upon one or more first images, creating a subsequent frame in dependence upon a second image, dividing said reference frame and said subsequent frame into a plurality of regions; comparing corresponding regions in said subsequent frame and said reference frame to a threshold thereby forming a difference measure frame composed of difference measure regions, identifying difference measure regions with a value substantially different from other of said difference measure regions, generating an alarm signal when a number of contiguous substantially different difference measure regions is greater than said target size parameter, and said number of contiguous substantially different difference measure regions is less than said global change parameter.