we know that the impression of an image does not vanish immediately from our retina but persists there for 1/16 th of a second. So, if we move still images of a moving object at a rate faster than this then the eye will perceive the object as moving. This is the phenomena which is being exploited in the process of carton film making. The still image of the objects in the cartoon films are played in a sequence at a rate faster than 16 images per second and our eyes perceive it as a moving picture.