![]() ![]() They provide the eye's color sensitivity. Physiological principles for effective use of colorĬurrent understanding is that the 6 to 7 million cones can be divided into "red" cones (64%), "green" cones (32%), and "blue" cones (2%) based on measured response curves. The blue cones in particular do extend out beyond the fovea.Īnatomical distribution of rods and cones The above illustration does make it appear that there are no cones outside the fovea centralis, but that is not true. These rods are responsible for night vision, our most sensitive motion detection, and our peripheral vision. At a few degrees away from it their density rises to a high value and spreads over a large area of the retina. On the other hand, the rods are absent from the fovea. Visual examination of small detail involves focusing light from that detail onto the fovea centralis. To them is attributed both color vision and the highest visual acuity. Measured density curves for the rods and cones on the retina show an enormous density of cones in the fovea centralis. Rods are absent there but dense elsewhere. Rod and cone distributionĬones are concentrated in the fovea centralis. Color perception has been successfully modeled in terms of tristimulus values and mapped on the CIE chromaticity diagram. Since the perception of color depends on the firing of these three types of nerve cells, it follows that visible color can be mapped in terms of three numbers called tristimulus values. Response curves for the three types of cones have been determined. ![]() The experimental evidence suggests that among the cones there are three different types of color reception. In the center of that region is the " fovea centralis ", a 0.3 mm diameter rod-free area with very thin, densely packed cones. The 6 to 7 million cones provide the eye's color sensitivity and they are much more concentrated in the central yellow spot known as the macula. However, they are not sensitive to color. The rods are more numerous, some 120 million, and are more sensitive than the cones. The retina contains two types of photoreceptors, rods and cones. The Rods and Cones of the Human Eye Rods and Cones ![]()
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