Numbers (Level 4)

Sun Dogs
Sun dogs on each side of the rising sun are caused by ice crystals in the sky on a very cold morning. Dispersion of light in the ice crystals also produces the rainbows. Since there are ice crystals in the air between the barn and the camera, the rainbow is also visible in front of the barn. There are many colors in this scene, produced in many different ways ó lights, objects, and scattering volumes. You can also notice the different colors of the snow. It is yellow where the rising sun is falling on it and blue in the shadows where only the scattered blue light of the sky falls on it.

How Many Colors Are There in the World?

The best answer is infinity!

Careful measurements of our visual systemís best performance have been made by psychophysicists (people who study human responses, like seeing color, to things in the world, like light). They have shown that we can see about 1000 levels of light-dark, 100 levels of red-green, and 100 levels of yellow-blue for a single, static viewing condition in a laboratory. This means that the total number of colors we can see might be about 1000 x 100 x 100 = 10,000,000 (10 million). A typical computer can display about 16.8 million colors to create full-color pictures, really far more than necessary for most situations.

However, the answer is not quite so simple. What color looks like is greatly affected by the viewing conditions. These conditions include the color of the lighting, the amount of lighting, and other colors in the scene. Colors also appear in different modes when they appear on different objects such as surfaces, light sources, or within volumes. Different people also have slight differences in the way they see color.

Since we can see as many as 10-million colors in a single viewing condition and the variety of viewing conditions and observers is endless, then the only truly correct answer is infinity. If we have 10-million colors, times 10-million lighting types, times 10-million lighting levels, times 10-million surrounding colors, times 6-billion people in the world, times 3 modes of viewing we get a really huge number. The result of that multiplication is 18 followed by 37 zeros (180,000,000,000,000,000,000,000,000,000,000,000,000), or 180 undecillion. That might not quite be infinity, but is close enough since all those estimated numbers are probably on the low side. And there is no way to exactly measure each of them. To learn more about the names of really big numbers, visit this site.

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Ever wonder ... What is the meaning of different colors?


Updated: May 20, 2010