Flashback to pre-school. You’ve got your chubby little baby hands in a blob of paint and suddenly you mix blue and yellow and discover that it turns into green. Fucking magic. You ask your parents why blue and yellow turn into green and they explain to you that when you mix certain colors together they make new colors. This seems perfectly logical, except for it’s only describing what you already knew. At five or six, you might care less. But then you stop asking questions. As adults we tend to accept these things. The sky is blue because it’s blue. It’s always been blue. Colors can change into new colors when mixed because that’s what they do. Why is everyone so satisfied with this?
In perception we’re learning about color, and what makes color… chromatic. We’re learning what properties color has and how some people can even hear color. As my professor says “Your brain can do a lot of cool things without drugs.”
The mixing of two colors together is called a subtractive color mixture. I’ll try to explain this as simply as I can so anyone can understand it. You’ve got some blue paint and some yellow paint. The paint is the color that it is because of the wavelengths that reflects. Different colors are prescribed to different wavelengths. We’ve all seen the color spectrum before.
Look to see where blue and yellow are. When you mix blue and yellow together, they subtract (hense: subtractive color mixture) the wavelengths except the ones that are associated with the color green. The reason that the visual experience of green that is created is because both blue and yellow reflect a bit of green. Notice that they are close together on the spectrum.
If the blue paint only reflected short waves and the yellow reflected only medium waves, the paints would not reflect a common color and when mixed they would likely turn black.
Simply put: When we mix colors we are mixing wavelengths, because because wavelengths determine what colors we see.