system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why does the human eye can see just the colors blue,green and red, while you need yellow,blue and magenta to mix all colors if you're painting?

In my biology class I learned that the human only reacts to blue-violett,green and red rays. But in my art class I learned that you or a printer for example needs to mix magenta,blue, and yellow together to get every other color. So why humans can see all color and printers can print all colors?
gpt
We see red green and blue, but since pigments are about removing light from white light, it uses different colored pigments which each selectively *remove* red, green, or blue from the light. Removing red light gives us cyan (which you refer to as 'blue' above). Removing green gives us magenta. Removing blue gives us yellow.

Since you are dealing with printing, four color process will also use black because it is difficult to get pure blacks by mixing real-life pigments together.