Rods/Cones Correction

[OmarShehata]

It's been pointed out by a couple people now that the explanation about why our eyes are more sensitive to luminance than color isn't quite accurate:

That’s also very similar to how human eyes work. The color receptors in our eyes known as “cones” are split into three types, each of which is mostly sensitive either to red, green, or blue. Rods, the other type of receptor we have in our eyes, can only detect changes in brightness, but they’re far more sensitive. We have about one hundred and twenty million rods in our eyes, compared to a measly six million cones.

Removing a bit of blue isn’t as noticeable as removing red or green. This is because of the six million cones you have in your eyes, about 64% are most sensitive to red, 32% to green, and only 2% to blue.

Brought up on Twitter here: https://twitter.com/etportis/status/1125128601689444352, https://web.stanford.edu/class/cs379c/archive/2010/stanford.lecture.04.pdf

So we need to change it so that:

• It does not incorrectly imply that rods are purely for luminance, since they actually don't contribute any info when the scene is bright, and that luminance is actually derived from cones as well