The RGB Color Model
When working with color light we have to do with the law of additive color mix. Corresponding to three types of cones of human retina it is based on three primary colors red, green and blue. Lighter shades of color result by mixing of primary colors. Yellow results by the mix of red and green, by green and blue cyan results and blue mixed with red results purple (magenta). If all three colors with fully intensity and equal portions get together they will complement to white. See also: Color Perception
Every color dot of a screen that exploits the additive color system is put together of three dots that can radiate a primary color with variable intensity in each case. Because they are too small from a normal distance to be recorded individually by the eye, it mixes the three dots together inevitable under the law of additive color mix.
The RGB Color Model is based on the additive color mixing procedure. On 24 bits color depth has every primary color 256 intensity grades (0..255), so that totaling 2563 = 16777216 = 224 colors can be represented.
