Compensation of illuminant tilt variation for texture classification

The paper uses theory and laboratory experiment, to show that directional illumination used during the image acquisition process, acts as a directional filter of three dimensional texture. It is shown that the directional characteristics of image texture are not intrinsic to the physical texture being imaged, as they are affected by the direction of the illumination. The implications of this to texture classification are then investigated using a set of Laws´ [1980] operators. Finally, a scheme for the compensation of effects caused by changes in illuminant orientation is proposed and evaluated