Seeing Colors

How many colors can we see?

Some scientists say that we can distinguish about 16 million colors. Others say only about 1 million. The real answer depends on how you define what is meant by discriminating color.

If your definition is the minimum color change needed to perceive a difference in color, the answer is about 16 million. Our ability to discriminate colors depends on where they are found on the spectrum (their wavelength), how bright the color is, how large the color area is and how close the two colors are. But generally speaking, at the red end of the spectrum, we can distinguish a change of 1 nanometer (1 billionth of a meter), at the violet end, we can distinguish a change of about 5 nanometers, and at the middle (yellow-green) of the spectrum we can distinguish a change of about 2 nanometers. Blue is somewhere between 2 and 5. At the very ends of the spectrum (deep reds and purples) it is over 5 nanometers.

However, if you only want to do color matching, as in finding a color of touch up paint to match your car color, the answer is that we can distinguish about 1 million colors.

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