The Color-Sensitive Cones

In 1965 came experimental confirmation of a long expected result - there are three types of color-sensitive cones in the retina of the human eye, corresponding roughly to red, green, and blue sensitive detectors.

1965年，实验终于证实了一个长期预期的结果——人眼视网膜中存在三种对颜色敏感的视锥细胞，分别对应于红、绿和蓝敏感的探测器。

Painstaking experiments have yielded response curves for three different kind of cones in the retina of the human eye. The "green" and "red" cones are mostly packed into the fovea centralis. By population, about 64% of the cones are red-sensitive, about 32% green sensitive, and about 2% are blue sensitive. The "blue" cones have the highest sensitivity and are mostly found outside the fovea. The shapes of the curves are obtained by measurement of the absorption by the cones, but the relative heights for the three types are set equal for lack of detailed data. There are fewer blue cones, but the blue sensitivity is comparable to the others, so there must be some boosting mechanism. In the final visual perception, the three types seem to be comparable, but the detailed process of achieving this is not known.

painstaking experiments have yielded response curves for three different kinds of cones in the retina of the human eye. The 'green' and 'red' cones are mostly packed into the fovea centralis. By population, about 64% of the cones are red-sensitive, about 32% green-sensitive, and about 2% are blue-sensitive. The 'blue' cones have the highest sensitivity and are mostly found outside the fovea. The shapes of the curves are obtained by measurement of the absorption by the cones, but the relative heights for the three types are set equal for lack of detailed data. There are fewer blue cones, but the blue sensitivity is comparable to the others, so there must be some boosting mechanism. In the final visual perception, the three types seem to be comparable, but the detailed process of achieving this is not known.

When light strikes a cone, it interacts with a visual pigment which consists of a protein called opsin and a small molecule called a chromophore which in humans is a derivative of vitamin A. Three different kinds of opsins respond to short, medium and long wavelengths of light and lead to the three response curves shown above. For a person to see an object in color, at least two kinds of cones must be triggered, and the perceived color is based on the relative level of excitation of the different cones.

当光照射到锥体上时，它会与一种由名为视蛋白的蛋白质和一种名为色苷的小分子组成的视觉色素相互作用。在人类中，色苷是维生素A的衍生物。三种不同类型的视蛋白分别对短、中和长波长的光作出反应，并导致上图中所示的三条响应曲线。要使一个人能感知物体的颜色，至少需要两种类型的锥体被激活，感知到的颜色基于不同锥体激发水平的相对程度。