The human eye contains a lens and a retina. The retina contains light sensitive receptors known as rods and cones. The primary purpose of the rods is to provide night vision, while the cones work at higher levels of light intensity. The cones contain photopigments, also known as photoreceptors, which are sensitive to red, green, or blue. The physiological properties of the nervous system dictate the sensation of color.
Humans are sensitive to a range of wavelengths.
Wavelengths are not colored, yet color results from the interaction of light and our nervous system. Wavelengths that produce different colors are focused at different distances behind the lens. The lens does not transmit all wavelengths in the same way, exhibiting less sensitivity to the shorter wavelengths, which has the effect of absorbing blues. Conversely, we are more sensitive to the longer wavelengths, which is exhibited by an increased sensitivity to yellows and oranges. Colors that differ only in the amount of blue do not produce clear edges.