Calculating lightnesses in a single depth plane

The experiments in this paper demonstrate that "Early Vision" mechanisms ca n account for the appearance of three "Diamond Wall" demonstrations, withou t reliance on apparent illumination, transparency, apparent depth, and junc tions. The first set (Section 2) demonstrates that simultaneous contrast an d the Katz-Albers effect can explain the appearance of a Diamond Wail displ ay. The second set (Section 3) reviews the "Straight Edge" experiments desi gned to show changes in lightnesses consistent with perceived illumination. These experiments showed that very-low-spatial-frequency sampling causes b oth these effects, and White's effect. The third set (Section 4) applies co mplex Early Vision models to images associated with the "High Vision" light ness hypotheses. The argument is that flat displays, which are perceived as flat, require a quite complex visual mechanism just to account for the pro perties of flat lightnesses. Any experimental verification of the existence of High Vision lightness mechanisms should be tested first with realistic complex Early Vision models. The results show that Early Vision mechanisms can account for appearances in Diamond Wall experiments. If Early Vision me chanisms can explain these results, then these experiments cannot be used a s evidence for the existence of High Vision mechanisms. (C) 2001 SPIE and I S&T.