For the longest time we didn’t have to pay a lot of attention to the way we talk about color. The modern display technologies capable of showing more vivid shades have, for better or for worse, changed the rules of the game. Once esoteric ideas like a gamut or a color space are becoming increasingly important.
A color can be described in many different ways. We could use words, list amounts of CMYK printer inks, enumerate quite flawed HSL and HSV values, or even quantify the responses of cells in a human retina. Those notions are useful in some contexts, but I’m not going to focus on any of them.
This article is dedicated entirely to RGB values from RGB color spaces. It may seem fairly restrictive, but considering the domination of displays as the medium for color presentation, it is a pragmatic approach and it ultimately won’t prevent us from describing everything we can see.
Good explanation about color spaces by Bartosz Ciechanowski.