The human eye is composed of rods and cones which interpret photon intensities and transmit that information to the brain. Rods are useful for night vision and are sensitive to gradients of gray and discerning motion. For color detection, the eye uses its 7 million cones (64% red, 32% green and 2% blue).

New studies are showing that every human retina is dramatically different with regards to red and green cone distribution. These conclusions were made with adaptive optics imaging allowing researchers to photograph the individual structures of the retina. Despite the differing populations of cones, test subjects all perceived color gamuts to be the same. The implication of this is that the human brain provides post-processing effects to visual information, much like a digital camera's algorithms, prior to storage or cognitive processing.

The eye itself is still largely responsible for the images we see. The differences in a cat's eye include large numbers of rods and a larger pupil which provides excellent night vision. Their eyes operate in a color gamut favoring longer wavenlengths in the violet and blue spectrum. Dog eyesight is also largely a physical trait, in the same color gamut as a cat but with placement allowing a wide field of view. Thus, eyesight and visual perception are a combination of both physical structure and cortex filtered elements.