>That depends. In rgb-calculations cyan is the opposite of red, if for
instance
>you were using another hightech multimedia-tool like for instance
fingerpaint
>you'd have green as the opposite of red.


This is not entirely true. There is a common misunderstanding, that additive
colors (light) behave different from subtractive (pigments). It is correct
that green is the opposite of red, but the misunderstanding lies in what is
"red" and what is "green".

Here is a show-off from a class I attended once. (This is for information,
and not to make a fool of anyone. It is not easy to come up with all this
one ones own; I know. :) )

Usually, you say that red, blue and yellow are mixed together to make black.
In pigment-theory, yellow is a primary color, which is true, because yellow
pigment is the pigment that reflects everything which is not blue! Red is a
primary color in both systems, however the color is not the same! Red is the
pigment that reflects all colors but green. The red pigment reflects
red+blue light when illuminated with white light, and thus "red" is not
actually red, but red+blue=magenta! "Blue" pigment is really cyan. We have:

"red" (magenta) pigment = <1, 1, 1> - green
yellow pigment = <1, 1, 1> - blue
"blue" (cyan) pigment = <1, 1, 1> - red

The opposite color is the color on the "other side" of the color wheel. Now,
we can see that red is the opposite of green in common language, but it is
actually magenta that is the opposite color of green and vice versa.

If you open the standard color-picking tool in Windows or any graphical
package, you can see the color-wheel, and verify this.

Observe that opposite colors also exists in light-systems, as opposite = <1,
1, 1> - original.

Simen.

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