1. An image processing apparatus, comprising: a sensor which senses occurrences of a predetermined event in a plurality of image pixels and which outputs event signals in response to the sensed occurrences; a time stamp unit which generates time stamp information by mapping pixels corresponding to the event signals to a time at which the event signals are output from the sensor; and an optical flow generator which generates an optical flow based on the time stamp information in response to the outputting of the event signals by the sensor.