Color Vision and Trichromaticity

Beginning with Sir Isaac Newton's first experiments with light and prisms, it has been apparent that the light we see - especially white light - is composed of a relative mixture of light of distinct colors. Perhaps the most astonishing fact, however, was that all light perceptions could be replicated by mixing just three colors - the primaries red, green, and blue.

In the late 19th century Thomas Young and Hermann von Helmholtz proposed what remains the most fundamental theory of color vision. The Young-Helmholtz theory states that the three primary colors selectively stimulate three different types of cells in the retina, now known to be cone photoreceptors. These cells provide the basis for all color vision, and are the first input cells in the visual pathway.

The first applet in our tour experiments with the trichromatic theory of color vision. Notice that the intersection of the circles combines their colors, and when all three primaries intersect, we get a full-color picture. Experiment with the hue, brightness, and saturation of the primaries.