Digital Camera Color and Vision

It's easy to demonstrate that any color can be considered a combination in determined proportions of only three basic zones of the visible spectrum, red green and blue. This can be proven by combining different proportions of light of each of these colors. If we project a beam of light of each color on a screen, we can see that the result of the sum is white light. Graduating the proportions of the three basic colors we can obtain any other. Color vision is produced precisely as a result of the combination of nervous stimuli of these three types; in the retina, color sensors are divided in sensitivity to green, red and blue. (An alteration in the functioning of one of these sensors produces a defect in color perception known as colorblindness ).

Color and Photography
In photography the same principal is followed as in sight: to define or reproduce any color, some determined colors or regions of the spectrum are chosen as a base: primary red, primary green and primary blue. Each one

constitutes a third of the visible spectrum. The sum of the light of the three in the same proportions gives white light, and each one has nothing in common with the other two. Any color can be considered as a sum of determined proportions of these three primary colors. In all possible colors, there are three which are of special importance in photography: the ones obtained from the sum of two primary colors. This way the three secondary colors are obtained; each one of them can be considered:

• the sum of two of the three basic colors (two thirds of the visible spectrum); or as well,
• white light minus the color that isn't in the sum (white light minus a third of the spectrum).

The colors obtained are:

• yellow:
• sum of red and green;
• white light minus blue;
• magenta:
• sum of red and blue;
• white light minus green;
• cyan:
• sum of blue and green;
• white light minus red.