How We See Color

How We See

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. It contains all the wavelengths of energy we are familiar with under different names, such as; Radio waves, microwave, infrared, visible light, ultraviolet radiation, X-rays, and gamma waves. Within the electromagnetic (EM) spectrum is the small band of what we call visible light.

The typical human eye perceives colors in the 380 to 720 nanometer (common unit to describe the light wavelength) range of the electromagnetic spectrum, and has peak color sensitivities in the red, green and blue color ranges.  Light input at the retina is changed into electrical impulses that travel to the back of the brain via a complex system of electro-chemical relays. There is such a range of “normal” human vision that no two people perceive the same color the same way. At the back of the eye, or retina, there are about 120 million rods, and roughly six million to seven million cones. Rods are 1,000 times more sensitive to light as the cones, but they are not sensitive to color. They perceive images as black, white and different shades of grey. Cones, on the other hand, contain one of three pigments that are sensitive to either red, green or blue light. Each cone contains a pigment that absorbs a color wavelength.  

So why do we perceive a color differently? Some of the personal difference is genetically passed down to us. Some color perception is biased by our own memory of what a specific color should look like. At other times a color can change appearance according to the colors surrounding environment (color context). So how do clients and businesses that produce or reproduce color talk to each another about such a fragile subject? By using standards and well-defined measurement tools when talking about color.