What is the RGB model?
The most well known model is the RGB (Red-Green-Blue) one. All the colors can be obtained by blending various amounts of each of these 3 basic colors. This system is used by TV cathode ray tubes and computer monitors. Each pixel is made of 3 small adjacent phosphors emitting respectively red, green and blue lights when excited by the electron beam. This model is said additive because each color is obtained by adding the lights emitted by each phosphor. For example equal values of red + green give yellow. In computer images, the best that can be done is to code the intensity of each color on one byte. Therefore the emission of each phosphor can have 256 distinct levels (from 0, for black, to 255 which is the maximum of emission for this color). Each pixel being made of 3 phosphors, this technique allows the coding of 2563 = 16,777,216 colors. This mode is usually named: 16 millions of colors, true color or 24 bit color mode. You must understand that an image can’t have more colors than
