A multi-stage color model.

The first stage of our model has three cone types, with L:M:S cones in ratios of 10:5:1. In the second stage, retinal connectivity leads to three pairs of cone-opponent, and one pair of cone-nonopponent systems. At a third (cortical) stage of color processing, the S-opponent cells are added to or subtracted from the L- and M-opponent units to split and rotate the one effective parvo geniculate response axis into separate RG and YB color axes, and separate luminance from color. We also discuss changes with eccentricity, and connectivity based on correlated neural activity.