An abbreviation for “Red, Green, Blue.” The RGB color model is an additive method of creating colors by utilizing red, green, and blue light combined in various ratios. The very idea for the model itself and the abbreviation “RGB” come from the three primary colors.
Primary colors are based on the physiological response of the human eye to light. The human eye contains photoreceptor cells called cones, which normally respond best to yellowish-green, green, and blue light. The color yellow, for example, is perceived when the yellow-green receptor is stimulated slightly more than the green receptor, and the color red is perceived when the red receptor is stimulated significantly more than the green receptor. Although the peak responsiveness of the cones does not occur exactly at the red, green and blue wavelengths, those three colors are described as primary because they can be used relatively independently to stimulate the three kinds of cones.
One common application of the RGB color model is the display of colors on a cathode ray tube or liquid crystal display such as a television picture tube or a computer monitor. Each pixel on the screen can be represented in the computer’s memory as independent values for red, green and blue. These values are converted into intensities and sent to the CRT or LCD display. By using the appropriate combination of red, green and blue light intensities, the screen can reproduce many colors between its black level and white point. Typical display hardware used for computer monitors uses a total of 24 bits of information for each pixel. This corresponds to 8 bits each for red, green, and blue, giving a range of 256 possible values, or intensities, for each color. With this system, approximately 16.7 million discrete colors can be reproduced.