Motion Segmentation is a means of seperating a moving objects in an image from a static background. The background image is accumulated over multiple images , and the invariant values of each pixel are taken to be the background either after a certain number of frames or as a median value for the pixel over say 20 frames. An object which moves dynamically from frame to frame will change the value of pixels in the image and obscure the background which it moves across and an outline of the changed values can be used to segment out moving objects from the non moving background. S.Humble