人们用眼睛观察客观世界。由于自然界生物的进化,使人和许多高级动物的视神经不但能从物体各点发光的强弱来辨别物体形象,而且还能对不同波长的光作出选择性的反应,这就是色觉。色觉是人眼重要视觉特性之一。试验表明,就分辨阈值考虑,人大约能区别200种黑白等级和750万种色;就 People use the eyes to observe the objective world. Due to the evolution of the living things in nature, the optic nerve of people and many advanced animals not only can distinguish the image of the object from the intensity of the light emitted from each point of the object, but also selectively responds to the light of different wavelengths. That is color vision. Color vision is one of the important visual characteristics of the human eye. Experiments show that in terms of discrimination threshold, people can distinguish between about 200 black and white levels and 7.5 million colors