RGB
The RGB system stands for Red, Green, Blue and was created for electronics like
cathode ray tube computer screens and color TVs, where a monitor emits differing
amounts of red, green, and blue to produce a desired color. Think of RGB as a means
of describing a particular color in terms of the amount of each primary color you
would need to put onto a black surface in order to produce the color. Because the
initial surface is black and you are adding primary colors to it, the system is described
as an “additive” color system. The color is managed by specifying a number between
zero and 255 for each of the three primary colors. So if you were to put a full amount
of red onto the black surface but no green or blue, you would wind up with an RGB
of: 255 0 0 (red). As the number decreases, the brightness of the color decreases. So
an RGB of: 150 0 0 will still be red, but a darker red than 255 0 0. These numbers
are referred to as “RGB triplets” throughout the book. More RGB triplet examples
are shown in Figure 5.3.