Color rank and census transforms using perceptual color contrast

Rank and census transforms provide high resistance to radiometric distortion, vignette, and noise because they are based on the relative ordering of local pixel intensity values rather than the pixel values themselves. These transforms are widely used in many computer vision applications. An important step of computing these transforms is to compare or rank two grayscale values, which is very much like measuring color difference in color image. Color difference between two color points at any part of a uniform color space corresponds to the perceptual difference between the two colors by the human vision system. Based on this idea, we propose to use perceptual color contrast to implement color rank and census transforms and achieve this without significantly increasing the amount of data to process and without complicated computations. Furthermore, we demonstrate the feasibility of using these new transforms to find correspondences for stereo vision.