What color is rgb(173, 25, 33)? I wanted to get better at guessing via intelligent practice. This is a quick little game I built to test (and train) my brain to extrapolate color from code:
http://melodylu.github.io/rgb-yay/
There's a small gray bar at the bottom to help players get in the right ballpark for how bright the right answer is, but perceived luminance of colors is tricky, so it might not help much.