Re: Primary colors and basis vectors

Open any program that uses color, and allows you to define your own by
using three numbers. (generally there are 2 forms. One uses red / blue
/ green, the other is hue / saturation / luminosity)

In the former case, doubling a "vector" doubles the brightness.

Of course, these use a linear scale (often from 0 to 255- yielding
24-bit color). If you want to keep it open ended, then you would
probably want some sort of negative-exponential scale, so max intensity
is at 0, and getting dimmer as you go outward. For negative values,
since we are talking about color here, I would say you should use the
color-inverse. (for example, if the "positive x" axis is green, then
the "negative x" axis should be magenta (= white - green))

.