Contrast independent motion detection using ´inverse pair´ spatio-temporal edge detectors

Detection of motion by methods such as background differencing is bedevilled by noise-induced changes which can appear as motion signals. It is therefore important to have methods which extract motion in a more fundamental way. To achieve this it is necessary to remember that motion is a spatio-temporal (3D) phenomenon. This problem is approached by applying ´inverse pair´ filters, the outputs of which are combined to give a response which is invariant to contrast. The output response is also invariant to direction of motion within the image.