FIGURE 9-38 Opponent-Color Contrast Response (A) A red–green color-sensitive RGC responds weakly to white light on its center and surround because red and green cones absorb white light to similar extents, so their inputs cancel out. (B) The cell responds strongly to a spot of red light in its center as well as to red’s paired wavelength, green, in the surround. (C) It is strongly inhibited by a small spot of green in its center. (D) The RGC responds very strongly to simultaneous illumination of the center with red and the surround with green. (E) It is completely inhibited by the simultaneous illumination of the center with green and the surround with red.