Confused about color theory/wheel?

Question

I see that Adobe's color wheel https://color.adobe.com/create doesn't match neither RGB neither RYB color models. Ex: If I choose RGB = 255,0,0 I get a shade of Green as a complementary color. But I I choose RGB = 0,255,0 I get a Magenta instead of Red?

What is the contemporary color model taught in Art schools and the one that, say photographers use (thinking of Fashion photography for example)? RGB or RYB?

Is there an online tool that matches either of these models and is widely used?

Answer 1

Three questions here.

I.

This is a personal opinion: Adobe likes o complicate things.

Yes, that is not RGB or RYB models. It is not Lab. When you have a model that is not standardized, and you do not provide any explanation on why that "new" model is "better" on anyway, it is a bit useless. If you like the results, it's ok to use it, but again, IMHO, do not use that specific tool to understand color theory.

There is a chance that the color wheel tries to simulate RGB values for CMYK colors or something like that. The perceptual value of Cyan on an RGB monitor does not correspond to the pigments currently used in the different printing industry. But again, if they do not make a minimal effort to explain the logic behind that wheel, there is no use for it, except just a tool.

Take a look at these other questions.

Is there a name/formulae for the hue-circle scaling Adobe is using with "Kuler"

Is there a standard for color wheels?

---

II.

It is hard to generalize. A lot of people use an RYB model, especially, IMHO for children and in art schools, when the main tool is physical paint.

But remember that this is not an "exact" model. The tones are used in a general way, which is the yellow yellow? and which tone is the correct blue?

In painting, you use different tones of yellows, blues, reds. You rarely try to use only primary colors.

When printing technology is taught, you have to use the CMY-RGB model.

On the current digital photography world, the RGB model is normally used, and a bit of Lab.

---

III.

An online tool to do what?

You are probably referring to websites to make palettes or color schemes.

There are some other websites, making a search here on stack exchange you can find some lists.

widely used

The RGB-CMYK color wheel is pretty standard, not on online websites but in programs themselves.

But color is a bit subjective, it is a perception thing, not only a "mechanical" construct. This is why we have different models. RYB, RGB-CMYK, HSB, HSL, Lab, Munsell.

Answer 2

The color wheel looks like a saturated LCh wheel. Maybe normalized to RGB maximum. You can find a similarity wheel here, although its not continuous. LCh is a polar transform of the Lab color model. Lab is (sort of) perceptually uniform (meaning that distance between 2 colors is as visually as distinguishable as another color as far away from this point, and its does not work as well for long distances as small). The problem is that LAB does not say anything about how to interpolate colors just how hard they are to differentiate.

Now Lab is based on what color science says to us (not color theory). And it keeps changing since measurements get better and there are many different basis for the system. Now, this wheel should have better color uniformity as far as how humans perceive it. The LCh transform is a bit naive at times so its not perfect since scientifically there is not really a good definition of a color wheel.

If there is no definitive wheel what about color theory?

Answer 3

Hmm, I just looked at the Adobe color website and noticed that the color wheel there does not conform to the normal color wheel found in Photoshop or Illustrator or any other graphical programs. They have shifted yellow by around 10 degrees to the left giving you different answers to complimentary colors.

I don't know why they have done this since it goes against their own graphics programs. Perhaps they're trying to emulate some sort of human perception? Perhaps they are trying to make it conform more to the RYB model but not completely? I don't know. But the following answer covers all computer graphics programs (including ones from Adobe) but not the Adobe color website:

Understanding the color wheel - what we learned at school

You mention you are familiar with the color wheel we learn at school where the primary colors are RED, YELLOW and BLUE:

                                          Red
       Red                        Orange   |   Purple
        |                                \_|_/
       _o_        ---------->             _o_
      /   \                              / | \
  Yellow   Blue                   Yellow   |   Blue
                                         Green

CMYK

Well, we need to modify it a bit. Because it turns out that Red and Blue are not really primary colors since you can get red by mixing Magenta with Yellow and you can get Blue by mixing Cyan with a bit of Red. So The modified color wheel uses printing colors: CMY:

        Magenta
     Red   |   Blue
         \_|_/
          _o_
         / | \
  Yellow   |   Cyan
         Green

The thing to realize is that this CMYK model not only applies to screen printing but also actual paint mixing. You can do the preschool color-wheel experiment again with Cyan and Magenta instead of Red and Blue and you will find that you can get Red by mixing Magenta with Yellow. Note though: you will need fairly pure pigments for this to work as expected since impurities tend to add brownness (yellowness) to mixes. But printers mix spot colors using this formula (this is what Pantone colors are - a standard description of how to mix pigments).

RGB

Now, if you look carefully at the modified color wheel, it looks exactly like the color wheel used by Adobe programs. This is the HSV color model.

If you look even closer you will notice that RGB and CMYK is just complements of each other:

        Magenta                 Magenta
     Red   |   Blue                |           Red     Blue
         \_|_/                     |              \_ _/
          _o_            ==       _o_       +       o
         / | \                   /   \              |
  Yellow   |   Cyan         Yellow    Cyan          |
         Green                                    Green

So, any RGB color can be understood by understanding this color wheel. For example, there is no Yellow in RGB. But notice that Yellow is the opposite of Blue. So, to get Yellow you subtract blue from a color:

rgb(100,80,10)  is a "yellowish" version of rgb(100,80,120)
            ^                                           ^

If you use this color wheel as a mental model it is easy to understand RGB and print colors. It is different from the color wheel we all learned in kindergarten but only a bit different (by around 60 degrees). It is still the same concept.