Operating instructions:
Select a true-red tetrachromatic color via the "True-Red Tetrachromatic Color Sphere - Locally Trichromatic Hue Circles". You can click on any sphere's color to select a "double color" that appears below. Copy this "double color".
Paste the "double color" into the "True-Red Tetrachromatic Color Painter" and you can paint with it.
Everything else is self-explanatory. For further insight into understanding the 4D tetrachromatic color space visit: