RGB Color Model

In the retina of the eye, there are three kinds of color receptors, called cone cells. The three kinds of cone cells are sensitive to the short, medium, and long wavelengths of visible light, respectively. The RGB color model approximates the way human vision encodes images by using three primary color channels: red, green, and blue. Emitted light sources such as CRT monitors, flat-panel displays, and video projectors use the RGB color model, as do image-capturing devices such as video cameras and computers.

The RGB color model is additive, which means the red, green, and blue channels combine to create all the available colors in the system. When all three primary color values are the same, the result is neutral, or grayscale. For example, if all three primary colors are 0 percent, the result is black. If all three primary colors are 100 percent (the maximum value), the result is white.

When all three primary color channels are nearly the same strength, the result appears neutral with a slight color cast, depending on which channel is the strongest. For example, if the value of the red channel is higher than the value of the blue and green channels, the result is a slightly red image. Secondary colors are combinations of two primary colors: red plus green is yellow, green plus blue is cyan, and blue plus red is magenta.