1. A method for determining whether a moving object is accelerating or decelerating comprising the steps of: i) sequentially inputting images of a predetermined area, ii) extracting a moving object from said images based on the differences in said images, iii) for each said image, calculating a representative point of each moving object and the expected range of the representative point for that object in a subsequent image, iv) for each said moving object, determining that said moving object is accelerating or decelerating when the location of the representative point for the object is outside of the expected range in said subsequent image.