How the Eyes and Brain Process Color
We take color and its perception for granted, but have you ever thought about how the processing of color takes place in the eyes and brain? It’s really pretty fascinating.
Both the eyes and the brain work together in order to translate the things we see out in the world into color images. The eyes contain light receptors that transmit relevant signals to the brain, and this in turn produces internal sensations and perceptions that we know as color.
It’s All About Wavelength
The truth is that color is not actually inherent within any object. Scientists like Isaac Newton noted years ago that the phenomenon of color is not a given; instead, each object’s surface both reflects and absorbs all possible color wavelengths. Only the colors that are reflected from the object are the ones that we can perceive.
For example, when we see an object that is yellow in color, it is not that the color yellow is within it; rather, the object’s surface is reflecting yellow wavelengths and absorbing all of the other color wavelengths. In the same way, objects that appear black are absorbing all color wavelengths, and white items are actually reflecting all color wavelengths away.
When it comes to light, the primary colors are red, blue and green. Combining equal amounts of these three tones of light results in the color white. Every other color in the spectrum of visible tones are produced by a combination of these three in different measures.
Rods, Cones and the Retina
The retina of the eye is located at the back of the eye’s interior and covers about 65 percent of the eye. The retina is light sensitive and even considered to be a part of the brain. The retina has literally millions of rods and cones, which are light sensitive cells. Rods assist with processing black and white information, while the cones assist with color perceptions.
There are three types of cones, and most are located in the retina’s center. There are around six million cones in the human eye, allowing for the perception or color as well as sharpness. The three types of cones correlate to short, medium or long light wavelengths. They work in partnership with connector nerve cells and send information to the brain so that it can discern and interpret colors.
The rods and cones of the eye process light and make them into nerve impulses. These nerve impulses are then passed along the optic nerve to the brain’s cortex where we interpret them as the various colors.
Warm vs. Cool
The eye and brain are able to perceive more variation in warm colors than the cool ranges. The reason for this is that two-thirds of the eye’s cones interpret the longer wavelengths of lights such as reds, yellows and oranges.
Interruptions in Color Perception
Around one percent of women and 8 percent of men have some measure of trouble in perceiving color, sometimes called color blindness. Many of these people aren’t aware of their issues with perception. Some can still perceive the range of colors, but the information is transmitted differently to their brains.
The most common color perception impairment or color blindness is called “red and green dichromatism,” which means that the colors red and green are just about indistinguishable. Other color pair blending is also possible, but it is rare for people to be completely unable to perceive color differences.