Chromatic Stereopsis

One approach to developing faster, more robust stereo algorithms is to seek a more complete and efficient use of information available in stereo images. The use of chromatic (color) information has been largely neglected in this regard. Motivations for using chromatic information are discussed, including strong evidence for the use of chromatic information in the human stereo correspondence process in the form of a novel psychophysical experiment which we have performed. Specifically, we measured the minimum disparity needed to produce a reversal in apparent depth in ambiguous chromatic "wallpaper" stereograms. Our results indicate that chromatic information plays an important role in the stereo correspondence process when luminances variations are present. To investigate the potential role of chromatic information in computational stereo algorithms, a novel chromatic matching constraint -- the chromatic gradient matching constraint -- is presented. Then, a thorough analysis of the utility of this constraint in the PMF Algorithm is performed for a large range of sizes of the matching strength support neighborhood, and the performances of the algorithm with and without these constraints are directly compared in terms of disambiguation ability, matching accuracy and algorithm speed. The results demonstrate that chromatic information can gready reduce the matching ambiguity, while significantly increasing both matching accuracy and algorithm speed.