Abstract

Using a sum of cosine grating (N = 1,2,3,4,5,6,8, or 16) with the same contrast and spatial frequency but with an orientation difference of 180/N between components, we measured Michelson contrast sensitivity as a function of relative grating size, calculated as Af² and expressed in the number of square cycles. The increase in contrast sensitivity with Af² was found to become less steep and saturated at a smaller number of square cycles with increasing N. This suggests that spatial integration of the detection mechanism became less effective with increasing stimulus orientation bandwidth. When contrast sensitivities were transformed to energy sensitivities we found that when Af² < 3.14, energy sensitivity was constant for all values of N.

© 1991 Optical Society of America