Characteristics and new measurement method of NCSFs of individual color mechanisms of human vision

We propose a new method for determining neural contrast sensitivity functions (NCSFs) of isolated color mechanisms based on the measurements of wave-front aberrations and isoluminant color contrast sensitivity functions (CSFs). Compared with the traditional method, this technique avoids the coherent noise and speckle noise, which are brought by the interference of laser beams, and has great flexibility for the measurements of NCSF of different color mechanisms. Our experiments indicate that the mean NCSF and CSF of the red mechanism are higher than those of the green mechanism, respectively, while those of the blue mechanism are the lowest. However the relative heights of the peak of NCSF and CSF between red and green mechanisms vary in subjects. There are some individuals whose peak values of NCSF and/or CSF of green mechanism are higher than that of the red mechanism. The NCSFs and CSFs of isolated color mechanisms all exhibit the similar characteristics and variation tendency. With the statistical average, the NCSFs of the red, green and blue mechanisms are higher than the corresponding CSFs in the whole spatial frequency. Compared with the corresponding CSFs curves, the peaks of the NCSFs of isolated color mechanisms shift toward higher spatial frequencies, especially for that of blue mechanism which has a largest shift of 3.9 c/deg.