Previous evidence has shown that the number of L and M cones in retina varies significantly between subjects. However, it is not clear how the variation of L/M ratio changes the behavioral performance of the subject. A model of transformation of data from retina to visual cortex for evaluation of various L/M cones ratios is presented. While L/M cone ratios close to 1 brings the best performance for one of postreceptoral (magnocellular) channels, we showed that the performance in the second channel (parvocells) will improve when the ratio furthers away from 1. Effects of different ratios of S were also explored.