hey you!

i want to write a little programme that explains the visual effect of complementary colour addition.
that after you look at a lamp for a few minutes, your eye (the retina neurons) supplements the complementary
colour, so that you see a black form, shaped like the lamp you have looked in before. like seeing the white
wall pink after starring into a green neon tube...

to illustrate that effect the programme should look like that:
in the background there will be an illustration of an eye that looks directed to a colour palette.
if your cursor ("the eye") is over a red area of the palette the white background should dye in a tone that is
complementary aqua mixed with the white of the wall (a pastelle colour).
the compl. colour is always the addition up to 100%, so if "the eye" "looks" at RGB (255, 0, 0) = red
the background should turn into (0, 255, 255) = aqua mixed with white ( => saturation between 10 and 20 %).

but i don´t know if RGB ist the best colorMode to be used for that and to be honest, i don´t have a clue
how to write that function.
as i am quite new into programming (started mainly with html, css and some javascript) i´d really be thankful
if you could help me out with that!

thanks a lot!
Nina