Color Wheels are wrong? How color vision actually works
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RR Phantom
Location : Wasted Space Job/hobbies : Cayman Islands Actuary
Subject: Color Wheels are wrong? How color vision actually works Sat Apr 01, 2017 10:49 pm
Color theory is a little obsession of mine. You’re here for startup advice, but this week I’m taking an indulgence. Leave a comment if you want to see more or fewer of these little distractions.
Why are artists special?
Ask any artist to explain how color works, and they’ll launch into a treatise about how the Three Primary Colors: red, blue, and yellow form a color “wheel:”
Why “wheel?” All other colors are created by mixing these three colors in certain proportions, they’ll explain. In particular, mixing equal quantities of each pair of Primary Colors produces the Secondary Colors (orange, green, and purple):
Continuing this process produces the infamous color wheel you probably learned in school; a pretty, symmetrical, satisfying device in which each hue melds seamlessly and linearly into the next:
Unfortunately, none of this stands up to even minor scrutiny.
For example, open up your desktop printer and you’ll see something quite different:
Three colors of ink which, when combined, produce all others: cyan, magenta, and yellow. (Black is included as a money-saver — black is the cheapest and most common color; it’s cheaper to have a black cartridge than to dump ink from the other three.)
But wait! I thought the “Primary” colors were red, blue, and yellow, not cyan (bluish-green), magenta (bluish-red), and yellow. So this is a different set of three colors which are “Primary,” yet still generate color wheels containing all the other colors. So what does the “Primary” designation really mean?
Also it’s not as simple as saying “any three colors can produce all the others” because that’s clearly not true (by experiment). And it’s not as simple as saying “any three colors will do, they just have to be equally spaced around the color wheel,” because yellow is common to both the painter’s and printer’s wheel, yet the other two primaries differ completely (red and blue are primary in the painter’s wheel but secondary in the printer’s wheel.)
TVs and computers are different yet again. If you stand close to a CRT (non-flat-screen), you can see that every pixel (or “dot”) is really three tightly-packed colored phosphors: red, green, and blue.
If you’ve done computer graphics you’ve been forced to name colors using these “RGB color values;” true geeks automatically think “yellow” when they see #FFFF00. (If it’s intuitive to you that #A33F17 is burnt orange, you are indeed a God among men. I’m looking at you, @soopa.)
This leads to yet another system of three “Primary” colors generating all the others, and another color wheel. This one is a little easier to explain — ink and paint are subtractive (adding cyan, magenta, and yellow yields black) whereas colored light is “additive” (meaning if you blast red, green, and blue you get white):
Still, we have yet another color wheel in which two (but not all three!) “primaries” match those of the artist’s wheel and none match those of the printer’s wheel.
Subject: Re: Color Wheels are wrong? How color vision actually works Sun Apr 02, 2017 12:44 am
Love the thread!
Now I can terrorize interior decorators, painters, artists, et al.
RR Phantom
Location : Wasted Space Job/hobbies : Cayman Islands Actuary
Subject: Re: Color Wheels are wrong? How color vision actually works Sun Apr 02, 2017 2:32 am
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Also see this comment...
Petr Stanicek
Thanks for the article. I studied a lot about the color theory when I created my color application, and I think I understand why the classical arts used the RYB wheel even if—from some points of view—it might seem yellow–blue should be the opossite colors. But they aren’t perceived as opposites, in fact.
You can try a simple experiment: if you stare at a solid color area for a while, and then you close your eyes, you will “see” the opossite color. If you stare at yellow and blue, you won’t see blue and yellow. Your own eyes can tell you the opposite for yellow is purple, and the opposite for blue is orange. You can try it directly on this page: find this picture above, the one with yellow and blue stripes in the middle and those orange squares on both sides. Lean to the display so that your eye distance is about 20–30 cm (up to one ft) and stare at the picture for 30–60 seconds. Try to keep your eyes as still as possible. Then close your eyes and relax. You should see the image on your retina in inverted colors. Instead of blue you’ll see orange, and purple/violet in place of yellow.
There is also a practical reason to deny the 4-primary-color RGYB model. Often, as an artist, you use not only the opposite color to make a contrast, but also surrounding colors to make lighter, softer contrast. It works great with the RYB wheel: for blue, you can pick either the opposite orange to make the strongest contrast, or surrounding colors from red to yellow for softer accents. The effect is pleasant and it’s perceived as nice color combination – i.e. like this: http://colorschemedesigner.com/#3L31Tw0w0w0w0
In the RGYB model, it works the same for red and green. But if you pick blue and use yellow as the “opposite”, you shouldn’t pick colors from both sides of the yellow. You will get unbalanced and often unpleasant combinations, like blue+orange+green, which are more agressive, not recommended by classical color theory to be used together (unless you are creating something agressive on purpose). You should choose only one side: either use the yellow-orange side, or the yellow-green side. You should avoid using a blue color with both yellow-orange and yellow-green accents together.
For the same reason both the RGB, and the CMY wheels fail with geometry used for pleasant color combinations. The classical RYB color wheel is thousands years old and used by artists through millenia. There are many good reasons why the colors are organized exactly this way. Even if physics sometimes says otherwise.
However, many thanks again for the physical and physiological background, it’s very useful and interesting reading.
Subject: Color Wheels are wrong? How color vision actually works 
Sat Apr 01, 2017 10:49 pm
