May 18, 2018knowledge, opinions/rants, technologyadditive color mixing, blue, colour primaries, green, subtractive colour mixing, yellows.westland

So some people say yellow and also blue do green. And also you will uncover other answers that say the yellow and blue do black. How have the right to this be?

Well, we require to recognize a tiny science to obtain to the bottom that this.

You are watching: What color does blue and yellow make

The figure below shows what happens once you mix an ideal yellow pigment with an ideal blue pigment. The blue dye reflects light perfect in around a third of the spectrum (and absorbs perfect in the other two thirds). The yellow pigment shows light perfectly in about two thirds that the spectrum (and absorbs perfect in the various other third).


Notice that through a real yellow colorant, it does not reflect perfect in the middle and also long wavelengths and it does no absorb perfectly in the brief wavelengths. It reflects and also absorbs come some level all the wavelengths but it absorbs an ext the much shorter wavelength and absorbs less the middle and longer wavelengths. The very same is true that a actual blue pigment; the does no absorb perfectly at the middle and also longer wavelengths. The consequence of this is the you don’t gain black if girlfriend mix blue and also yellow. Friend would obtain black if the pigments were ideal yet they are not. Us live in the genuine world. However, you definitely don’t gain a lovely bright eco-friendly as presented in the colour wheel through red, yellow and blue primaries. Friend would acquire a dark desaturated murky dirty greenish colour.

Now let’s see what happens as soon as we mix cyan and also yellow. We’ll start with the best colours.


That’s right. Mix cyan and also magenta renders blue. The cyan absorbs in one 3rd (the red third) and also the magenta absorbs in one third (the eco-friendly third) however neither absorb the short wavelengths.

So ultimately you can see that the ideal subtractive primaries are cyan, magenta and yellow since the cyan is red absorbing, the magenta is green soaking up and the yellow is blue absorbing. And also what is more, girlfriend now know why this is the case (rather than accepting dogma). You additionally understand why there is a relationship in between the CMY of subtractive mixing and also the RGB the additive mixing.

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John R Reinert Nash says:

This short article focuses on pigments, and also why CMY make much more logical primaries for pigments. The explanation is heavy (as any kind of press printer will tell you!), and the RYB wheel as something taught in elementary college art course really does should be updated. If us can obtain these guys to perform a video clip on CMY, it would go a long way:

as a color scientist that straddles the human beings of image capture (RGB!) and also print (CMYK and also more!), however, we should absolutely proceed to teach that yellow and blue do green, yet make the clear the this functions for light, and not for this reason well because that paint. I recall that Kodak walk dabble in CMY color filters because that a digital camera, however RGB filters (Bayer filter in particular) because that light really do seem to have actually won the day for camera catch (with some exciting experiments in adding an “emerald” fourth pixel color by Sony that never quite appeared to take it off).