Determining motion fields under non-uniform illumination

Abstract Two realistic methods based on a generalized conservation equation of image brightness are proposed for the accurate determination of motion fields under non-uniform illumination. The conservation equation includes spatial and temporal derivatives of image brightness, a motion vector and a rate of brightness generation. The term for the brightness generation rate can represent non-stationarity of a brightness pattern during its motion under non-uniform illumination. By introducing an optical model and prior knowledge of non-uniform illumination the conservation equation can be solved. One of the two proposed methods assumes a stationary motion field under spatially non-uniform illumination. The other assumes local constancy of a motion field under temporally non-uniform illumination. The application to artificial and real image sequences confirms the usefulness of the proposed methods.