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.