Question

Explain how to use color coordinates to find the range of colors that can be expressed using three different colored (waveform) light sources and discuss what values should be chosen on the color coordinates if three monochromatic light sources are selected to maximize the range of color representation.

Answer 1

Based on the tristimulus theory of version, our eyes perceive color through the stimulation of three visual pigments in the cones on the retina. These visual pigments have a peak sensitivity at wavelengths of about 630 nm (red), 530 nm (green) and 450 nm (blue). By comparing intensities in a light source, we perceive the color of the light. This is the basis for displaying color output on a video monitor using the 3 color primaries, red, green, and blue referred to as the RGB color model.

Vertices of the cube on the axes represent the primary colors, the remaining vertices represents the complementary color for each of the primary colors. The RGB color scheme is an additive model. (i.e.,) Intensities of the primary colors are added to produce other colors. Each color point within the bounds of the cube can be represented as the triple (R,G,B) where values for R, G and B are assigned in the range from 0 to1

The color Cλ is expressed in RGB component as Cλ = RR + GG + BB

The magenta vertex is obtained by adding red and blue to produce the triple (1,0,1) and white at (1,1,1) in the sum of the red, green and blue vertices. Shades of gray are represented along the main diagonal of the cube from the origin (black) to the white vertex.