Figure 1 Figure 2

Truly a miraculous phenomenon, color vision has three basic requirements (Figure 1): A light source, the object to be viewed and a detector – the eye. Actually, the detector is an array of specialized cells within the eye’s retina known as rods and cones.

Rod cells outnumber the cones by about 20:1. Because they can respond to all wavelengths of visible light (Figure 2) at low illumination levels, they are responsible for our black-and-white night vision.

Our eyes contain three kinds of cones that respond to light in the red, green and blue regions of visible light, respectively. Together they cover the entire range of light from about 400nm up to about 700nm.

One interesting note: The cones are focused in a small region of the retina, and this feature enables us to see better in a well-lit area.