Contrast matching across spatial frequencies for isoluminant chromatic gratings

Contrast matching was performed with isoluminant red-green and s-cone grati ngs at spatial frequencies ranging from 0.5 to 8 c/deg. Contrast threshold curves were low-pass in shape, in agreement with previous findings. Contras t matching functions resembled threshold curves at low contrast levels, but became flat and independent of spatial frequency at high contrasts. Thus, isoluminant chromatic gratings exhibited contrast constancy at suprathresho ld contrast levels in a similar manner as has been demonstrated for achroma tic gratings. (C) 2000 Elsevier Science Ltd. All rights reserved.