As an aside, there is an optical illusion called a Benham’s top (or disk), which produces what are called Fechner colors directly in the brain, so do not need cones in the eyes to be seen.
https://en.wikipedia.org/wiki/Fechner_colors
Some years ago, it was discovered that people with total color blindness, who only see things in black, white and shades of gray, can still see Fechner colors.
They are amazed by perceiving colors for the first time, something that their brains can do even if their eyes can’t.
I remember reading an old account that in the days of B&W TV, Fechner colors could also be displayed on screen and had been used in some commercials. That might weird some people out... how is this black and white TV showing me color?
The effect does not seem to be standardized between people, or else maybe a Fechner color based color viewing system could be designed. Perhaps it could still be, but it would have to be tuned to the person.