The 90% Color Wheel

Third in a series of blog entries about color theory with live help from the ColorTheory (Step 3).  First_post,  Prev_post,  Next_post

The Yurmby (RGB, CYM) wheel is not the original color wheel, nor is it the most common color wheel. The most common is the one first proposed by Newton as part of his prism studies and refined from there. It defines three primary colors of Red, Blue, and Yellow, and secondary colors of Orange, Green, and Purple. Only 8% of the color wheels in Google image are Yurmby, 90% are the Traditional wheel, with 2% “other”.

The Traditional wheel has been in use for almost 250 years. The first three-color printing process developed in 1710 was based on RYB, with a four-color RYBK soon to follow.

There is no doubt that the Yurmby wheel is mathematically accurate as to how it represents RGB and CYMK colors. Why does the traditional wheel insist on being so useful that it has stayed in use for the last three centuries?

Let’s start by pointing out three big differences:

  • Traditional says that blue plus yellow makes green. Yurmby disagrees.
  • Yurmby says that red plus green make yellow. Traditional disagrees.
  • And finally, Traditional thinks that Orange deserves a lot more space than Yurmby does.

There are three things going on here. One is that color names are imprecise and the colors vary from color wheel to color wheel. I chose the colors for the Traditional wheel to match online versions of the Itten color wheel. Red and Yellow match, but there are differences in the Blue shades that mean that even in the Yurmby wheel, the “alternate” Blue is more greenish than the normal (in RBG) Blue, so blue plus yellow will result in something more greenish. Until the early 20th century with the development of artificial pigments, color creation was largely done by mixing natural pigments with their own quirks and hues.

A second issue is the eye optically mixes colors differently than pigments mix colors. Color scientists note that people do not perceive yellow as a mix of red and green, and have developed experiments to show that this is embedded deep in our brain structure and not just a matter of training or culture.

And third is that our eyes are better at distinguishing certain shades than others. They are particularly good at distinguishing shades of orange and red. So cognitively, the Yurmby wheel doesn’t give enough room for the oranges, and provides too much room for the green shades.

So in some sense the Traditional wheel is a pragmatic compromise between the way that our eyes want to treat color, and the way that the external world wants to treat color. It’s not the only possible compromise, and we’ll see some other alternatives soon.

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