Magenta Ain't A Colour

Disturbing, yet cool.

beam of white light is made up of all the colours in the spectrum. The
range extends from red through to violet, with orange, yellow, green
and blue in between. But there is one colour that is notable by its absence.
Pink (or magenta, to use its official name) simply isn’t there. But if
pink isn’t in the light spectrum, how come we can see it?

Here’s an experiment you can try: stare at
the pink circle below for about one minute, then look over at the blank
white space next to the image. What do you see? You should see an
afterimage. What colour is it?