How come red & purple are on opposite, far ends of the electromagnetic spectrum, but when mixing colors together in kindergarten, purple is halfway between red & blue?

Question

Shouldn’t common sense dictate that either both be one, or both be the other?

In: 1934

Answer 1

So there’s two different “purple like” colours or what some might consider purple or a mix of red and blues

True violet and magenta

True violet has a specific wavelength of light , easy for computers to properly display and something easy to explain as just a specific wavelength of light. It’s something that exists in a sense that we can say X nm of light is violet. Our eyes can see that wavelength and it fires off our cone receptors in a specific way that our brain says violet

Magenta however , doesn’t actually have exist , there is no magenta wavelength but we can still see magenta. This is because the way our cone cells in our eyes work is a trinary system , you sometimes have 4 rare and they generally are red blue green yellow with yellow being the rarity in a small lucky portion of people

When light comes in that is red orange , it sets off our red cones heavily and our green cones very little (depending on how orange is compared to red). Our brain takes the relative level from both and averages and says “that’s orange” , more green cone firing off and you get closer to yellow and then proper green.

When you get red and violet light coming it sets off both are red and blue cones which if our brain just averaged them would give us something closer to yellow/green then magenta. But our brain knows that green is a thing and the green isn’t being set off , so our brain makes up a colour since it should average to be green but it can’t be green so it makes up magenta