Your mind maybe playing tricks on you!

[Andy]

Taking a BW photo of the image defeats the purpose of the illusion since the cyan is the key to the whole thing. I can dig up my "Psychophysics and physiology of color vision" notes or look in my Adlers Physiology of the Eye, but there is no red. Also, the world is flat, but everyone knew that.

[edgarspencer]

Though I doubt such a person exists; if one had never seen a can of Coke, would he still see 'red'?

[Andy]

Originally Posted by edgarspencer

Though I doubt such a person exists; if one had never seen a can of Coke, would he still see 'red'?

I suspect a person would given the cyan that floods the rest of the image. It's called lateral inhibition I believe where retinal cells determine edges and have an inhibitory response to one cell and excitatory response to neighbors.

https://www.animations.physics.unsw....ry-colours.htm