By equipping people with those two simple things, hue and brightness names, we had our language. So now if you hear red 60, you’ll know it’s a medium red, and if you see a really light shade of blue, you can guess it’s blue 10. The language is quick to learn and reasonably precise.
To solve this, we leveraged what we had already done with color naming and selection. Using our algorithm, we made our color lightness-to-darkness consistent across color hues, so that every color 0–50 is accessible (4.5:1) on black, and every color 60–100 is accessible (4.5:1) on white.