with some carefully considered exceptions the intensity discrimination data of the human eye fall into two classes : those with small test areas or with red light , which form a single continuous curve describing the function of the retinal cones alone , and those with larger areas , and with white , orange , and yellow light , which form a double curve showing a clear inflection point , and represent the separate function of the rods at intensities below the inflection point and of the cones at intensities above it .
C0015392
eye
C0035298
retinal