system
Given the following post, respond as if you're commenting on Reddit:
human
Why aren't pixels made up of 'RYB' LEDs instead of RGB ones?

Was wondering that since the 3 primary colours are red, yellow and blue would it not make more sense in some applications for yellow LEDs to be used instead of green LEDs for pixel based displays.
gpt
Additive versus subtractive color. RYB (actually Magenta, Yellow, Cyan) are primary subtractive colors. Red paint isn't red light, and yellow paint isn't yellow light. Magenta ink/paint is actually anti-green (it absorbs green), yellow is actually anti-blue, and cyan is actually anti-red. If you combine magenta and yellow paints you are really combining anti-green and anti-blue, so those colors are absorbed whereas red is reflected, so you get red.

However, the rules are opposite for additive colors where you are generating light that is mixed. Red is red, green is green, and blue is blue. Combing red and green light you get red-green light which is just yellow.

Hopefully that makes sense.

Edit: you can play around with this a bit on your own. For example, try mixing together different paint colors to see what the result is (hint: it's generally always darker). And try painting cards that you use to try to reflect light onto the same spot, or use ink to color a transparent filter over a flashlight and see what happens when you combine different light colors. Compare that to what you get when you mix the paints/inks together instead.