Of course, that’s a rough estimate. Depending on the lighting conditions, surface texture, and background color, people may be able to distinguish a few more or a few less shades. Note that the image at the top of this story is an optical illusion, in which the bar is actually one shade of gray. The graded background makes the bar appear to have different shades along its horizontal axis.
Meanwhile, human color vision is much richer. People are thought to be able to detect about 10 million unique colors. And some can see even more than that.
We wanted to share with you these bits of science trivia for no particular reason whatsoever. We learned them from a paper called “Biological versus electronic adaptive coloration: how can one inform the other?” The paper is about research into e-book display technology and is very cool. E-books are also a totally unrelated subject we just pulled out of thin air.