Sam Teaches Us About the Primary Colors

Sam
Josev It is worth noting that this is taught entirely wrong in school. The primary colors of light are red, blue, and green. That has nothing to do with physics and everything to do with biology. You have 3 light sensors in your eyes and those are the colors they detect. Other animals have 2 (dogs, for example) or 4 (most birds) kinds of sensors and they can see more or fewer colors than we can. Birds can see infrared and ultraviolet as well as distinguish between colors that you only get by mixing shades we can see with ones that are invisible to us. What happens if you mix green and infrared? We would see green, but what would a bird see? Some new color we can't perceive.

Then the primary colors of paint are often taught as red, blue, and yellow. That is just plain wrong. What colors are in your printer? Cyan (which is bluish, but much lighter and a bit more green), magenta (which is redish, but subtly closer to pink and purple) and yellow. (And also black, but that's just because it's hard to get a good black from mixing colors.) Those are the compliments to red, green, and blue and therefore the true primary colors... at least for typically sighted trichromatic humans.


Josev
Sam It does have everything to do with physics, otherwise we would not see colors, but I do agree that biology takes a major part in it too. About the primary colors, you sure that it is red, blue and gree? not red, blue and yellow. I did a little research and did found some arguments supporting yours but I also found arguments suporting that it is red, blue and yellow. You see, from red,blue and yellow we are also able to get every color we can perceive, and about the printer, doesent it have orange( yellowish with a bit of red) ? I didnt really understoos your argument using a printer as example, maybe that is because I dont have one hehe.


Sam
Josev Our eyes perceive red, blue, and green. That's why those are the primary colors of light. They are also used in things like computer and television screens that produce RGB color because those devices work by emitting light, so using that color scheme produces the cleanest results.

Colors that are produced by absorbing and reflecting light, like paint and ink, use CMYK as the color scheme. (K is black, which RGB achieves by just emitting no light at all). C is cyan, the color emitted if all red is absorbed and blue and green are reflected. M is magenta, when all green is absorbed and red and blue are reflected, and Y is yellow when all blue is absorbed and red and green are reflected.

So when you mix cyan paint, which absorbers all red light, with yellow paint, which absorbs all blue light, the only visible color reflected back is green, which is reflected by both colors.

The bastardization of this typically taught in schools just doesn't work and leads kids to mixing colors wrong with muddy results. Pure yellow and pure blue don't get you a pure green. Usually we call something between blue and cyan "blue", mix it with yellow and call the dark green result "green". It's close enough for kids, but there is a reason professionals use the cmyk color scheme. It is the one designed to work with human trichromatic eyes.

But if we were dichromats (which mildly color blind people are) and, for example, couldn't distinguish blue from green, the whole color wheel would look different. There would be 2 primary colors and people who could perceive the richness of 3 colors would wonder why we couldn't tell the difference. Similarly, for tetrachromats (which scientists suspect that a rare few human women are, but we know it is common in birds) they can perceive 4 primary colors, one of which we can't really distinguish in its pure form from the one we mix with other colors but it would look different to them, as would the colors you get when you mix with it.

Mantis Shrimp have 7 different kinds of light perceiving cones in their eyes and it was long believed that they experience MUCH richer colors with a rainbow that extends way farther in both directions and subtle in between colors we can't imagine. Although a recent study suggests that maybe their eyes work so differently from ours that the additional color perception cells aren't actually helping them see that many more colors. Still interesting to imagine though.


Sam
Josev BTW, I'm not certain of the history, but I would guess that some of the confusion stems from the fact that what we call the color we now call "blue" has changed over the centuries. When Newton labeled the colors of the rainbow, what he called "violet" is what we now call "blue" (as in roses are red and violets are blue). What we now call "violet" is closer to purple, which is a mix of red and blue (somewhere near magenta on a color wheel). Those colors are at opposite ends of the spectrum and therefore they cannot mix in a rainbow. Violet isn't even in the rainbow.

I've tried explaining to my kids what they were learning wrong about colors in school, but it is so ubiquitous that there's no hope of explaining the right information until they already know generally how it works. I have explained that not everything they learn in school is correct, but I've given up on correcting them about how colors mix until they're a bit older.


Luke
+Sam Red, blue and yellow, not green.


Sam
Luke Red, blue and yellow is what is commonly taught in school, but it is wrong. With normal human vision, the primary colors of light are red, green, and blue, hence your television and computer monitor uses RGB coloring to emit the appropriate color of light. For absorbing and reflecting colors in paint, kids are commonly taught red instead of magenta, cyan instead of blue, and yellow ( that one is correct). So kids learn red, blue and yellow, but professional printers use the real primary subtractive colors of cyan, magenta, and yellow (CMYK, with K for black added to make it easier and cheaper to print well). Thise are the true compliments of the additive primary colors observable to the human eye or red, blue, and green.


MangoTango
+Sam boy primary colors are red blue and yellow. It's not based on what the human eye perceives it's based on the colors that can't be made by combining other colors. Green is a secondary color. End of discussion.


Sam
MangoTango Nope. On your computer, make a picture with a swatch of red and a swatch of blue on them. Now print it. See the red and blue on the paper? Yes, but your printer has no red or blue ink. It has Cyan, Yellow, Magenta and Black (CMYK). It mixes the red and blue from those true additive primary colors in typical human vision.

When you think about it, not only does the idea that red, blue, and yellow are primary and that this is true independent of human physiology fail to hold up to testing, and not only do experts say that is wrong whenever asked, but it isn't even really plausible. What possible explanation could there be from all the wavelengths of light from microwaves to Gamma rays to x rays to infra red to ultra violet to radiowaves, etc. to have 3 wavelength play such an important role that happen to fall into the tiny sliver of the electromagnetic spectrum that we can actually see. The primary colors are primary BECAUSE that's what we see, because that is the colors our cones in our eyes have peak sensitivity for  (with a lot of complex detail left out). Just because you were taught something in school doesn't make it true. It is a simplification, using the more common red instead of magenta and the more common blue instead of cyan. But there's a reason your printer doesn't use those colors. The company that built that actually knows what they are doing.