Stereopsis due to luminance differences in the two eyes.

A local region in an image is seen as slanted when the two eyes are shown different luminance values in that region. The steepness of the slant depends upon the size of the region and the difference in the luminance values in the two eyes. Three examples where this phenomenon influences depth perception are given: (1) stereopsis without corresponding binocular luminance edges is shown to be a limiting case of the phenomenon; (2) edges less than 1 min arc apart can be seen in relative depth with respect to each other; and (3) regions that appear transparent or translucent can be seen in depth despite having all the luminance edges at zero disparity in simple stereo images.