The "REAL" Color Wheel

First, let me say that the quotes in the title of this piece are intentional. There is no one color system that can do everything. Over the centuries, there have been many color systems depending on the subject at hand, the available pigments, and the tastes of the people involved.

Before I launch into a tirade on the perceptions of color, I should give a little hint of my credentials. I spent years in the 3D graphics industry, writing software and studying mathematical modeling and translation of color systems. I've been formally trained in illumination engineering, learning more than sane people should know about how light is created, transported, received and observed, and how to measure each part of the process.

Here's an example of my 3D graphics playtime - a study in opalescence, the dispersion of different frequencies of light in different directions. In this piece, blue-cyan light disperses backwards and yellow-red light disperses forward through the body of a solid material. It's based on watching a candle flame interact with a glass of absinthe...


Enough on me and my hobbies, though...

In the study of light and color, the measurements and language get tangled very quickly. Are we talking about the color of light or the color of an object filtering or reflecting the light? Are we talking about actual frequencies of light and their combinations into spectra or are we talking about the single color that's percieved by the human eye? Thankfully, when most people talk about the color of an object, they are referring to the appearance of the color as seen by a human eye under white light.

In art school, we were taught a 12-color wheel. Red, Yellow, and Blue are the primary colors. Green, Orange and Purple are the secondaries. Between each of these are the tertiaries: Red-Orange, Yellow-Orange, Yellow-Green, and so on. We are taught that these lie across from each other in a color wheel and that these opposites are called complements.


This color wheel has been used to help in product and graphic design for over 100 years, but it isn't very helpful when it comes time to analyze complicated color interactions in dyeing and weaving.

Here are some typical questions that need to be answered:
- I've got a violet, but it's too bright and a little too red. What should I add to the dye to subdue the saturation and reduce the red?
- My woven piece has bright turquoise threads, but they look dark blue in the weave. What is making that happen? What can I do to make them look closer to the right color?
- My warp thread is a glaring chartreuse. What can I use in the weft to make it look more subdued and more green, but without a high-contrast look?

To answer these questions with some certainty and without a lot of testing, it it helpful to know how the human eye perceives color and how we can achieve the colors we want.

The human eye has three types of color sensing cells, called cones. Each type of cone can see only one color: Red, Green, or Blue. Color TVs, projectors, and computer monitors use this principle to display a full range of colors with only three colors of dots, one for each of the cells in our eyes. The entire color storage system of our computers is designed around representing levels of light that are perceived by human eyes.


Notice that these three colors are colors of LIGHT. The screens and projectors give off light. When they give off equal parts of red and green, our eyes see yellow. If you don't believe me, grab a magnifying glass and look at the yellow circle in the image below. The red and green dots on your screen are lit up. The blue dots are dark. See? This type of color mixing is called ADDITIVE because the red light ADDED to the green light makes our eyes see yellow.

Now, use your magnifying glass to look at the blue circle, opposite the yellow. Now you'll see that only blue dots are lit, and not the red or green. They are truly opposites in terms of how they affect the cells of our eyes.


When we are talking about colored objects it gets a little confusing. White light bounces from a white object with no change. Our eyes see white. For colored objects it's a different story. White light strikes the object. The pigment - paint, dye, ink, or whatever - filters out some of the light. In the case of yellow, it's the blue light that's getting filtered or absorbed. Blue light is not reflected so only the red and green light makes it to your eyes and you see yellow.

This type of color mixing is called SUBTRACTIVE because the pigment is REMOVING the color of light that's opposite it on the wheel.
- Cyan pigment removes red light.
- Magenta pigment removes green light.
- Yellow pigment removes blue light.

In the same way as we can represent any color of light with RGB values in the computer, we can represent any color of object with CMY values. (K, representing black, is added to make it easier on the printing hardware to render colors without saturating the paper with ink.) If you look at the dots of color on an inkjet print, you'll see that there are only the four colors of ink, CMYK.

You can do a similar exercise to magnifying the screen by printing red, green, and blue on white paper. Your magnifying glass will reveal that:
- Blue is made of cyan and magenta pigment. Cyan removes the red and magenta removes the green, leaving only blue light reflected to your eyes.
- Red is made of magenta and yellow pigment. Magenta removes the green, yellow removes the blue, leaving only red light reflected to your eyes.
- Green is made of yellow and cyan. Yellow removes the blue, cyan removes the red, leaving only green light reflected to your eyes.


Here are some nifty ways of thinking about pigments or visual mixing:
- adding pigments to an existing color will do one of two things:
- if the secondary color is less than 1/3 of the way around the circle, it will lead the main color around the wheel. (ie: Yellow will turn green with the addition of cyan.)
- if the secondary color is more than 1/3 of the way, it stops changing color and starts changing saturation. (ie: Yellow will head from green to black as the added color travels from cyan to blue.)

By following this scientific method of identifying and working with colors, it's easy to answer the questions above:
- If your violet is too bright and too red, add some cyan to pull it toward blue. Add a little bit of green, violet's opposite, to dull the saturation. (Bearing in mind that green is just yellow and cyan, so add a lot of cyan and a little yellow to achieve your final result.)
- Turquoise threads look dark when placed next to their opposite, red-orange. The redder the thread, the more likely that the turquoise will be pulled toward magenta, and therefore from true black toward blue. To make them look closer to the right color, pair them with colors that are nearer to themselves on the color wheel.
- To cure a grating chartreuse warp and trick the eye into seeing a greener cloth, use a weft thread that's just on the other side of green from chartreuse, a very green turquoise. This will work until you hit cyan. If you pass it, you are now heading toward yellow's opposite. Instead of changing just the hue, you will also be changing the saturation. The colors will look muddier and muddier until you get to the point that is opposite the chartreuse: dark purple.

Now, back to the art-school color wheel...



By calling red, yellow and blue our primaries, we are doing two major things - compressing the range of blue-green and extending the range of yellow-red. Just look at how many similar oranges there are and how few turquoises. We're also confusing light and pigment. Mixing pigments in the color of light leads to the phenomenon that we're all familiar with: grey, muddy colors. Remember in art class when your red and blue turned grey instead of purple? Now you know why it happened. We should have had cyan and magenta paint all along.

The 12-color wheel isn't "wrong", it's just not technically consistent in a way that leads to clear and simple decision-making.

For an exciting look at the development of color systems, including a few glimpses at how old this particular one is, spend some time reading The Creation of Color in Eighteenth Century Europe by Sarah Lowengard. In the chapter entitled Words for Color, you'll see a few examples of early color systems that have much in common with the art school 12-point color wheel still used today. And these studies are over 200 years old.