Algorithm for finding the color between two others - in the colorspace of painted colors

Question

When mixing blue and yellow paint, the result is some sort of green.

I have two rgb colors:

blue = (0, 0, 255)

and yellow = (255, 255, 0)

Wha

Answer 1

Actually, you get green from mixing (subtractively) yellow and cyan. Yellow is red + green (255, 255, 0), cyan is green + blue (0, 255, 255). Now make their opposite colors: blue (0, 0, 255) and red (255, 0, 0). Mix them additively and you get purple (255, 0, 255). Make its opposite and you get green (0, 255, 0).

In other words, you can get a subtractive mix as the opposite of the additive mix of the opposites of your two colors.