When a photograph is taken by a camera, it is called a physical process. But when we see color, we are actually having a psychological experience. The eyes receive an impression but do not see. It is the brain that sees. So when the image is brought to the brain, the brain cells have to take to mean this and make a judgment.
While we "see" in our brain, and therefore also "see color" in our brain, the brain still has to receive certain images from the eye. Our eyes are so constructed that they can perceive seven colors in the spectrum: red, orange, yellow, green, blue, indigo and violet. The rod cells on the edges of the retina can only discriminate brightness and darkness. The cone cells in the centre pick up the individual wave length of the colors.
By which process the eyes actually pick up the colors is still controversial. Science has not yet found this out to a satisfactory extent. But the "Young-Helmholtz theory of color vision" seems to explain it. According to this theory, the eye contains three sets of nerves. These respond to the primary colors of light: red, green and blue-violet. When yellow light reaches to the eye, the green and red sets of nerves are both stimulated, and the color yellow becomes visible.
While we "see" in our brain, and therefore also "see color" in our brain, the brain still has to receive certain images from the eye. Our eyes are so constructed that they can perceive seven colors in the spectrum: red, orange, yellow, green, blue, indigo and violet. The rod cells on the edges of the retina can only discriminate brightness and darkness. The cone cells in the centre pick up the individual wave length of the colors.
By which process the eyes actually pick up the colors is still controversial. Science has not yet found this out to a satisfactory extent. But the "Young-Helmholtz theory of color vision" seems to explain it. According to this theory, the eye contains three sets of nerves. These respond to the primary colors of light: red, green and blue-violet. When yellow light reaches to the eye, the green and red sets of nerves are both stimulated, and the color yellow becomes visible.
