A preprocessor system (10) reduces random noise in video pixels by providing a memory (19) arranged to store first pixels processed during a first time period. A motion detector (300) responds to differences between the first pixels and second pixels processed during a second time period after the first time period to generate corrected motion signals. A first filter (100) generates first filtered values in response to the differences and the corrected motion signals. An impulse detector (244) generates control signals in response to detection of impulses, and an impulse reducer (250) generates second filtered pixel values in response to the first filtered values and the control signals.