Home Forums The Learning Center Color Theory and Mixing Why are Red, Yellow and Blue primary colours?

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  • #467926
    Steve922
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        Because they can’t be mixed from any other colours, right? But why not?
        ISTM that in the colour spectrum, Orange and green are just as valid colours as R,Y or B – they are, after all just different wavelengths (or they reflect different wavelengths) of light.
        SO what is special about R,Y and B ? Why is it that from the colour spectrum ROYGB Blue and Yellow make Green, also Red and Yellow make Orange but Orange and Green don’t make Yellow?
        I’m guessing there must be a scientific explanation but can’t find one anywhere.
        Bear in mind, my question is not which colours are primaries but rather WHY are they?

        #767614
        GardenMaven
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            They are just starting points. See this site.

            http://www.colorsontheweb.com/Color-Theory/The-Color-Wheel

            I use cmyk myself

            “Art is the only way to run away without leaving home.” Twyla Tharp
            Sandi

            #767605

            In a very simplistic view, most people have three separate colour detector types in their eyes, for long, medium and short wavelengths. That in turn means you need at least three different source colours to span the spectrum that those detectors respond to.

            If you are looking for a scientifically sound but quite readable source for how it all works, try Margaret Livingstone‘s book, Vision and Art.(Amazon.com)

            It should be available at school and public libraries, if you live near one; but it’s not too expensive and definitely worth having. If you do get it, get the second edition (the one I’ve linked to)

            Cheers,
            Chris

            C&C of all sorts always welcome! (I don't mind rude or harsh criticism.)
            I suppose I have to do this too :p (my blog, & current work). My Visual Arts Nova Scotia page.
            Art is the most intense mode of individualism that the world has known - Oscar Wilde

            The primary palette: Attention, observation, memory, imagination, integration, execution

            #767620
            Humbaba
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                Just a side note, according to Jose M. Parramon, the three primary colors are:

                Magenta
                Yellow
                Cyan

                #767615
                davidbriggs
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                    I gave a presentation that discussed the history and basis of the RYB idea at the Munsell Centennial Symposium in Boston last year. You can download a pdf of the presentation from the Inter Society Color Council website:
                    http://www.iscc-archive.org/Munsell2018_Presentations/Briggs-Presentation-WhereIsColourEducationNow.pdf

                    Colour Online (hundreds of links on colour): https://sites.google.com/site/djcbriggs/colour-online
                    The Dimensions of Colour: www.huevaluechroma.com
                    Colour Society of Australia: www.coloursociety.org.au

                    #767610
                    budigart
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                        Humbaba . . . Parramon is right. He instructs beginning painters to use cad yellow medium, alizarin crimson and Prussian blue (yellow, magenta and cian) and white. You can hit about 97% of the colors you need with these colors. He gives an entire chapter in his book, The Big Book of Oil Color, to these colors and how to use them as well as mixing recipes for all other colors.

                        The simple answer to why r, y and b are primary is because these are the only colors you cannot mix with other colors. Or, put another way, all colors other than these can be mixed with combinations of these three colors.

                        #767607
                        Mythrill
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                            Humbaba . . . Parramon is right. He instructs beginning painters to use cad yellow medium, alizarin crimson and Prussian blue (yellow, magenta and cian) and white. You can hit about 97% of the colors you need with these colors. He gives an entire chapter in his book, The Big Book of Oil Color, to these colors and how to use them as well as mixing recipes for all other colors.

                            The simple answer to why r, y and b are primary is because these are the only colors you cannot mix with other colors. Or, put another way, all colors other than these can be mixed with combinations of these three colors.

                            Quinacridone Magenta (PR 122) is a much better primary than Alizarin (PR 83) is, simply because it makes brighter purples and cleaner oranges – not to mention its lightfastness, of course.

                            #767621
                            Pinguino
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                                Happy to see that David Briggs already weighed in, higher up. Read what he wrote. Do it.

                                #767599
                                Delofasht
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                                    Many thanks to David Briggs for stopping in to share his excellent presentation.

                                    Interestingly, RYB proponents will often tell a new artist to buy Phthalo Blue, Alizarin Crimson Permanent, and Lemon Yellow as their “primaries”. These colors are actually closer to the CMY colors: Cyan – Phthalo, Magenta – Alizarin, Yellow – Lemon Yellow. They mix to a very wide gamut and are basically impossible to mix at a high chroma from other pigments. As others have stated, Magenta (PR122) is a better magenta for mixing than Alizarin. I prefer a Yellow pigment that leans toward orange just slightly myself (PY151, 154, or 74 are all decent). Phthalo comes in a large range of subtly different hues, so picking your phthalo can adjust your mixing range quite a bit.

                                    - Delo Delofasht
                                    #767622
                                    Pinguino
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                                        If readers here ever tire of trying to discuss RYB versus CMY: Have a look at university-level discussions as to to whether Fe56 or Ni56 is the dominant nucleus in the stellar core of a large star, just prior to supernova. You will discover that this is either mis-explained or mis-understood, on a very widespread basis. It’s not that the science is unknown; it’s that the explanations are often badly-worded, or answer a different question than the one asked.

                                        No reason to believe that artists are the only ones confused! :rolleyes:

                                        #767609
                                        Anonymous

                                            I can clear up all the confusion with just a couple of paragraphs of absolute truth that can be easily understood.
                                            First thing is that all charts, wheels, etc. are all purely man made depictions of a psychological concept and therefore, totally of no use whatsoever in determining, or in predicting, or in proving that any color is a primary or not, so scratch those all of those from the git go, they just don’t apply.
                                            The reason is that when we look at these three, they are sensed as being absolutely pure and distinct colors. So a true primary red would look dead center red with no perception of any orange or violet.
                                            This is the quality that cyan and magenta do not posess.
                                            Cyan looks like a greenish leaning blue next to a true primary blue,
                                            and Magenta looks like a violet leaning red next to a true primary red, and they should because they cyan and magenta are mixtures of colors when talking about our visual perception, where as red and blue are not mixes.
                                            Red, yellow, and blue can’t be mixed from other, different colors.
                                            Mixing a red from magenta is not mixing from different colors at all, it is starting with a potent red, and neutralizing the inherent blue bias so that the remaining red is seen as a true primary red, ditto for making a blue from cyan.
                                            Yet you will see this false claim made everywhere. The reason this false claim is made is a rather lame attempt to justify the notion that cyan and magenta are primary colors and red and blue are not. However, it just does not wash, but it is nonetheless responsible for some of the confusion.
                                            The concept of primaryism is not a the function of potency or tint strenght of the available pigments that we are limited with, due to physical constraints, primaryism is a purely psychological phenomenon that only exists in our brains. It has nothing to do with how many colors a physical pigment is capable of mixing.
                                            Also, the notion that because a very potent, staining, transparent “red or blue family” pigment is capable of mixing a more intense violet than another has no credence in making that color, such as a magenta, a true primary color. Look at the orange that it mixes to versus using other reds, it makes a lame orange, and if it were a true mixing primary color then it would also make the most intense orange on the planet, but alas, it fails, not a primary, sorry about that. Same thing for cyan, try to mix a nice violet with it and you will fall short.

                                            #767623
                                            Pinguino
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                                                I can clear up all the confusion… etc.

                                                No, no no, you have it all wrong. This is the Internet. There is supposed to be confusion. :eek:

                                                Anyway: For those who have not heard of the no true Scotsman situation, you can look it up.

                                                If I understand Sid’s argument, Cyan and Magenta are not mixing primaries, because Cyan is really blue (just not a true blue), and Magenta is really a red (just not a true red).

                                                I’ll have some sugar on my porridge, please. :smug:

                                                #767598
                                                WFMartin
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                                                    Why are Red, Yellow and Blue primary colours?

                                                    Well, they aren’t, but most artists dislike hearing that. Well, truly one is: Yellow; the other two are secondaries.:)

                                                    wfmartin. My Blog "Creative Realism"...
                                                    https://williamfmartin.blogspot.com

                                                    #767624
                                                    Pinguino
                                                    Default

                                                        And now, for the secret truth that we’ve all been waiting for: There are no primary colors because there is no such thing as color. Bwa ha ha! :evil:

                                                        Or, to put that another way, not so devilish: There is no single theory of color, as it is context-dependent. :angel:

                                                        One prominent theory of human color perception is that there are four “unique” colors: red, yellow, green, blue. Anything else is perceived as a between-color. Thus orange is a reddish-yellow or yellowish-red. But yellow, spectrally between red and green, is certainly not a reddish-green or greenish-red.

                                                        In that theory, yellow and blue are perceptual opposities. In balance, the result is neutral gray, not green. Likewise red and green. The actual theory selects particular hues of the four unique colors. I believe that the unique red is a non-spectral color. The decision is made by showing folks color samples and asking them which of them is most representative of what they think of, when they think of that color.

                                                        But that has very little to do with paint mixing! Our pigments are far from being ideal colors. Although there are red and green pigments that can be mixed to a neutral gray, such is not the case for yellow and blue (even though such pigments could exist “in principle”).

                                                        I believe a lot of artists will tell you that most red-blue combinations do not mix to make good purples. In that sense, they are certainly not more “primary” than Cyan and Magenta.

                                                        If you use carefully-selected pigments that are undoubtedly red, yellow, and blue, then you will be able to get a certain volume (with black and white) in three-dimensional color space. If you use carefully-selected pigments that are Cyan, Magenta, and Yellow, then you will (with black and white) get a different volume in color space. Note that this concept applies to both additive and subtractive color mixing, but not in the same way or with the same results.

                                                        However, the RYB volume is not a subset of the CMY volume, nor vice-versa. There will be volumes in RYB space that lie outside the CMY space, and volumes of CMY space that lie outside the RYB space.

                                                        In general, the extra volume of CMY is greater than the extra volume of RYB. This is the reason why CMY are considered to be the premier mixing pimaries: They produce the largest (but not necessarily most useful) amount of color.

                                                        However, on an artistic basis, it may be the case that the extra CMY volume is in areas of color that are not needed, whereas the extra of extra RYB volume is in useful areas. Or, it may be the case that some widely-used colors, particularly orange hue (flesh, land) and blues (skies, water) are easier to mix with well-chosen RYB, than with well-chosen CMY. In this sense, RYB could be considered as primary colors for a particular range of useful artistic expression.

                                                        Side note: Seems to me that most children with a limited set of crayons will easily believe that orange is between red and yellow. Some may believe that green is between yellow and blue. But brown is not obviously a dark orange!

                                                        Afterthought: I sometimes believe that the reason so many folks say that red, yellow, and blue are the primary colors, is that Sister Mary Contrary rapped them over the knuckes in first grade, if they didn’t agree. :(

                                                        #767633
                                                        Richard P
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                                                            Yellow is special because a desaturated or darker yellow seems to lose that quality of yellowness we understand (when darkened it can appear greenish). In fact we don’t seem to have a concept of a dark yellow, it always seem to look greenish or orangish/brownish. :)

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