Readers of this blog know that we are kind of obsessed with color and color perception. Here is a great example of why color can never be an exact science and has a lot do to with your brains and how they perceive color. See if you can tell (without hitting the “read more” button) how many different colors these spheres have.
Whatever you guessed was probably wrong. Unless you said one.
This one sphere has the exact RGB values of (255,188,144), and it is kind of goldish-bronze. Here all the spheres look bronze. Now, go back to the top photos and look at the spheres again. Only this time focus on a single sphere. It looks bronze as well. Focus on a different sphere… Bronze again…
It is only when you look at the entire photo, the spheres assume different colors. Here is that same photo with no stripes going over the spheres.
Still not buying it? Look at this animated gif by syfy.com:
So why is this happening? Why do we see the color of the spheres change even though we know that they are all in the same color?
In a nutshell, we do perceive colors as they stand on their own, but also by contrast with colors around them. If I put up an image of a red square, then (assuming you have normal color vision) it looks red. But if I put up objects with other colors around it, the color we perceive changes a bit. That can be manipulated using stripes of different colors, for example. In the top row, note the colors of the stripes going across the balls. The left one has green stripes, the middle one red, and the right one blue. That changes how we see the balls.
This is called the Munker-White illusion (or sometimes just the Munker illusion), and it’s a powerful one. When you’re not looking directly at the balls, the color of the stripes pulls the color of the ball toward it, in a manner of speaking, so the green stripes make the ball look greener.
Perhaps the most mesmerizing illustration of this illusion is this video by thehardmenpath:
— thehardme (@thehardmenpath) June 16, 2019
If you want more here are some more illusions by Prof. David Novick: