why I don’t like the colour wheel

There are many reasons why I don’t like colour wheels of the type shown below:

The first reason is because it perpetuates the myth that the subtractive primaries are red, yellow and blue whereas the fact is that red, yellow and blue produces a rather small gamut of colours. It is certainly not the best choice of subtractive primaries though it is taught as dogma in many art and design schools and throughout children’s education. The problem is that whenever two colours are mixed together there is saturation loss; that is, the resultant mixture ends up being more desaturated than the two components were. The saturation loss is greatest when mixing colours on the opposite side of the colour circle where the resultant mixture can be almost grey. However, for certain choices of primaries, the saturation loss is greater than for others. If red, yellow and blue are used as the primaries then of course it is possible to generate any other hue. However, there is significant saturation loss and the above colour wheel gives completely the wrong impression. It suggests that mixing blue and yellow together, for example, results in a really bright vivid green.

The reality of pigment mixing is much more like the triangular colour wheel shown below:

In the above diagram it can be seen that mixing together yellow and blue results in a really muddy dark green. The purple resulting from mixing blue and red is almost black!! Now it is possible to mix together a blue and a yellow to get a better green. For example, mixing a greenish blue with a yellow will give a much more vivid green. Mixing a bluish red with a greenish blue will result in a lovely purple. We have a name for a greenish blue and a blueish red – we call them cyan and magenta. A much better colour gamut is obtained if we start with the primaries, cyan, magenta and yellow.

Footnote: Some people may look at the triangular colour wheel and think that the reason the colours are dull is that the red, yellow, and blue primaries used are not ‘pure’ enough. Nothing could be farther from the truth. If it was possible to make really vivid and bright red and blue pigments then the resultant colour gamut would be even smaller. Fundamentally, red, yellow and blue just don’t make good subtractive primaries.

8 thoughts on “why I don’t like the colour wheel

  1. All true, and if you tear apart your cereal box, you’ll see from the printer’s test strips they use magenta, cyan, yellow and black as their subtractive primaries. That said, the colour wheel above is aesthetically pleasing. High chroma primaries of Red Yellow and Blue for some reason (either through nature or nurture) seem to give, me at least, an in built satisfaction, that other colours don’t. Gems, coloured glass and transparent plastics always held fascination for me as a child. So is this learnt, or is it to do with the nerve response of our cone cells, or something else? Those in design and marketing seem to have figured out that babies and children are attracted to red yellow green and blue primaries.

    1. I agree that there is a certain psychological strength and saliency about red, yellow, green and blue. RYGB are the unique hues. Orange is not unique; it always looks like a mixture of red and yellow. Though a red can be yellowish or bluish, it is possible to have a red that looks pure, as if it is not a mixture of other colours. Likewise for yellow, green and blue.

      The power of these four colours is partly why they are found in many brands and logos. Look at the google logo, for example. To answer Simon specifically, I think unique hues result from neural processing of cone signals.

      However, the fact that RYGB look pure (in that they look as though they do not result from mixture) coupled with the eroneous assumption that the primaries need to be pure results in the mistaken belief that the primaries are red, yellow and blue.

  2. Not sure I agree totally. The colors on the color wheel can be bright enough for teaching basic concepts of how colors interact. I also think it depends on the quality of paint.

    1. Well, that’s sort of my point. The colours on the wheel are too bright. They suggest that if you mix a blue and a yellow you get a lovely bright green when you do not.

  3. haha, funny post.

    Personally I got sick of being annoyed my such mistakes on color theory/practice on the www. But recently (I am teaching colors for a few months) I bought some of such cheap “primary colors” in an art shop and we did that exact same test. Then I made them compare the almost-black blue made of reddish magenta and cheap phtalo blue with a beautiful pure greenish ultramarine blue pigment binded in tempera. We also measured in CIELAB with a spectro, and plotted the entire thing: the gamut of these “primaries” and the point of the ultramarine, very far below.

    Funny that I just discovered your blog, maybe you would be interested by mine, who knows…

    Best

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