Gamma-rama

Gamma-rama

In case all this gamma talk hasn’t already blown
your mind, allow me to clarify how monitor
gamma and human vision work together. The
question often comes up—why is middle gray
18% and not 50%? And why does 50% gray look
like middle gray on my monitor, but not on a linear
color chart?
It turns out that your eyes also have a nonlinear
response to color—your vision brightens low light,
which helps you to see where it’s dim, a survival
advantage. The human eye is very sensitive to
small amounts of light, and it gets less sensitive as
brightness increases. Your eye effectively brightens
the levels, and objects in the world are, in fact
darker than they appear—or, they become darker
when we represent their true linear nature.
The fact that 18% gray (or somewhere around that
level; there is some disagreement about the exact
number) looks like middle gray to your eye tells
us that the eye does its own gamma correction of
roughly 0.36: 50% x 0.36 = 18%.