By now everyone has seen "The Dress" -- the famous ugly dress in San Francisco that seems to change colors depending on who is viewing it. See
I am not at all convinced that this is a "real" thing -- I think it's a case of using PhotoShop to lighten or darken the color saturation in the photo and spreading out into a flurry of linkstorms on social media.
However, this is the real deal and it will blow your mind. Take a look at this picture:
See those squares with letters "A" and "B"? You are not going to believe it when I tell you that those squares they are on are exactly the same color. But go ahead, use a color picker of some kind in a graphics program and you'll find that both squares are a neutral gray with RGB factors of "R=120 G=120 B=120"; in Hexidecimal it's "#787878", on both squares. In other words, the SAME color.
The eyes are the easiest things to fool. Yet another reason why so-called "eyewitness testimony" is worth a lot less that we are told in court that it is.
Thanks to Color Wheels are wrong? How color vision actually works for this example.