 It is used as a dissimilarity measure in stereo matching, where one-dimensional search for correspondences is performed to recover a dense disparity map from a stereo image pair.When performing pixelwise image matching, the measure of dissimilarity between pairs of pixels from different images is affected by differences in image acquisition such as illumination bias and noise.Even when assuming no difference in these aspects between an image pair, additional inconsistencies are introduced by the pixel sampling process, because each pixel is a sample obtained integrating the continuous light signal over a finite region of space, and two pixels matching the same feature of the image content may correspond to slightly different regions of the real object that can reflect light differently and can be subject to partial occlusion, depth discontinuity, or different lens defocus, thus generating different intensity signals.