less_retarded_wiki/color.md

Color

Color (also colour) is the perceived visual attribute of light that's associated with its wavelength; for example red, blue and yellow are colors. There is a hugely deep color theory concerned with the concept of a color.

TODO

What Is Color?

This is actually a non-trivial question, or rather there exist many varying definitions of it and furthermore it is a matter of subjective experience, perception of colors may differ between people. When asking what color really is, consider the following:

• Are non-primary colors true colors, or just mixtures of the primary colors? Red, green and blue are the three primary colors, the ones we can mix all other colors from. Many will say yes, non-primary colors are colors. But hold on.
• Are non-spectral colors colors or just mixtures of spectral colors? Spectral colors are the colors with a single wavelength (e.g. red, orange or violet), other colors (like pink) are just mixtures of these. Again, probably yes.
• Is saturation part of color, or a separate attribute? I.e. are e.g. green and greenish gray different colors, or same colors with different saturation? Now it depends.
• Is black a color, or rather a lack of a color? E.g. in computers it is usually treated just as another color, but real world black is really the absence of any light.
• Is white a color? If we are using a subtractive color model, the argument is the same as for black (white paper is really just lack of any color on it).
• Is e.g. gold a color? Or just yellow with a lot of specular reflection? In real world many things may be called to have a gold color, but in computer graphics we would likely separate the color from the light reflective attribute (such as metalicity).
• Is transparent a color?
• Is intensity part of color (especially in context of e.g. HDR)? For example we might say both Sun and paper are white, but still Sun's color is much "stronger" -- is it therefore a "whiter white" than that of a paper?
• Are colors not perceivable by average human colors? Many animals see colors we can't see (e.g. those in infrared spectrum), but there are also rare cases of humans (so called tetrachromats) who see many more colors than usual thanks to a mutation.
• Are impossible colors colors? Interestingly there exist colors perceivable by average humans which however cannot naturally be seen due to "physics" -- they can however be seen with "eye hacks". Do we count these too?
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