11 Replies Latest reply on Dec 15, 2006 9:51 AM by agbanks

    RGB or RYB?

    Stu Maschwitz Level 1
      What's the thought behind using an RGB wheel for Kuler rather than the Red, Yellow Blue (subtractive) color wheel that all my color harmonics books use?

      An example of a tool that uses RYB: http://wellstyled.com/tools/colorscheme/index-en.html

      I don't know if there's an emerging wisdom that compliments generated in RGB space are somehow as valid as those found in RYB, but I think Kuler should at the very least have an optional RYB mode. And so does my third grade art teacher!

      -Stu
        • 1. Re: RGB or RYB?
          Level 7
          The Red, Yellow, Blue taught in primary school is just a simplification of Cyan, Magenta, Yellow (the subtractive primaries) taught to children who don't know the terms cyan or magenta yet, and haven't quite grasped the difference between mixing inks and mixing light.
          If you use Cyan, Magenta and Yellow as your color primaries -- that is valid. But Red, Yellow and Blue are not primary colors. Red, Green and Blue are primary colors for light - hence their use in your TV set, digital camera, computer display, etc.

          How can you tell that things don't really work with the color wheel as taught in grade school? Well, that simplified colorwheel says that red and green are compliments. But complimentary colors should mix to form a neutral color. Red and Green mix to form yellow (as light) or brown (as ink). Red and Cyan mix to form a neutral color in all cases, or magenta and green mix to form a neutral color in all cases. Technically, Red and Green are a split compliment. Red and Cyan are true compliments, and Magenta and Green are true compliments.

          It is sad to see so many painters continuing the confusion with their own color wheels. But many of the painter's color wheels and painterly color theories date from before there was any significant understanding of human color vision, or light for that matter. Now that there is some knowledge of human color vision and how light or pigments interact, color theory in art is also changing and correcting many long standing inaccuracies.
          • 2. Re: RGB or RYB?
            Stu Maschwitz Level 1
            OK Chris, but how confused are those painters really? They can't mix cyan and magenta paints together to make cobalt blue, can they?

            Are you really saying that every book on my shelf about color theory is wrong because additive color mixing has become more common than subtrative?

            I am very interested in this -- the question of how the RYB color wheel relates to CMY has been on my mind lately.

            It's going to be a lot of work reprinting all my xmas cards in red and cyan...

            -Stu
            • 3. Re: RGB or RYB?
              Level 7
              They weren't super confused. They tried to break things down into an ordering system without understanding how the human visual system actually ordered things. And they got really close based just on personal preference for various colors and simple experiments with mixing paints. (BTW - I can mix good cyan and magenta inks to make something that you cannot visually distinguish from cobalt blue. Of course, it'll be a metameric match and can be distinguished by it's spectral characterisitics.)

              Subtractive color is just as valid as additive color -- but many older books mislabelled the colors (calling Magenta "Red" and Cyan "Blue"). Then compound that with mistakes like "Red is a compliment of Green" and you end up with some long standing confusion about how color really works.

              The RYB of your childhood really should be MYC aka CMY.

              Theme colors for holidays and such are different. Even if Red and Green are not true compliments, they are still the traditional colors for Christmas (with smaller amounts of white, gold and sometimes silver).
              • 4. Re: RGB or RYB?
                3ABNPublishing Level 1
                There is a program for the Mac called Color Consultant Pro that offers both "artistic" and "scientific" color wheels, which correspond to the RYB and RGB models. The "scientific" one is functionally almost identical to kuler.

                The color of the primaries is not the only difference. In the RYB model, a larger percentage of pure hues are in the ink gamut. RGB cyan doesn't exist in it at all, the colors between yellow and red are more spread out, and the colors between the primaries are darker, deeper colors (as opposed to lighter, brighter colors in the RGB model). I assume this is because the artistic color wheel is based on a substractive ink model, versus an additive light model.

                Before and After magazine, widely respected in print circles, has a RYB-based color wheel that can be downloaded in PDF format from their website:

                http://www.bamagazine.com/ColorWheel.asp

                I think scientifically/mathetically, the color wheel on kuler is perfectly accurate. However, it does produce colors outside the printable gamut. The subtractive-based color wheels have less of this problem, but the question is: Do the same principles of color matching apply to both? (They both yield different combinations of matches for any given base color.)

                Personally I find the "scientific" model gives more pleasing results, although not always. Some of the RYB model matches look quite nice.
                • 5. Re: RGB or RYB?
                  Level 7
                  Yes, RYB will be more in gamut: because it's really CMY, as I already explained.

                  As long as you're not working with a specific ink set, you will always be able to make colors outside the printable gamut of that specific ink set.

                  It's not "scientific" versus "artistic", just additive versus subtractive (different ways of specifying the same color).
                  • 6. Re: RGB or RYB?
                    kodia Level 1
                    Hi Chris.

                    In theory your rant about about primaries and mixing is absolutely right..
                    Practically speaking, however, you're mistaken.

                    As an old-school airbrush artist I have mixed thousands of colors in the pre-photoshop era. Cyan, magenta and yellow are great primaries for inks. But they don't work for opaque colors. After years of mixing and experimenting with opaque colors my palette was finally simplified to 7 colors to reach a maximum gamut: a greenish and a orangish yellow, a greenish and purplish blue, a magentaish and orangish red and black. No magenta, no yellow, no cyan. Trust me, I was well aware of color theory at the time and I would have used magenta and cyan if they had worked.

                    Furthermore, from perceptional point of view it makes perfect sense to use blue, red and yellow as primaries. The human eye is perfectly capable of pointing out a pure blue without traces of violet or green, a pure red without traces of violet or orange and a pure yellow without traces of green or orange. However, the human eye is unable to point out pure magenta or cyan.

                    Don't get stuck in additive vs subtractive theory. There are other, practical ways of working with color....
                    • 7. Re: RGB or RYB?
                      Stu Maschwitz Level 1
                      OK Chris, you've weighed in on this and provided some interesting points, but I would love to hear from some other Adobites on this one. Whether you're technically correct or not, there's a large and active body of color study based around the RYB model, including most authoritative books on the subject. If Adobe is taking the stance that this has all been a mistake, that is important to know. Whose "baby" is Kuler? Is it designed to spearhead new thought in color theory or to be a handy tool that flexibly fits into, and expands upon, existing wisdom?

                      -Stu
                      • 8. Re: RGB or RYB?
                        Stu Maschwitz Level 1
                        quote:

                        Originally posted by: Chris Cox
                        ...BTW - I can mix good cyan and magenta inks to make something that you cannot visually distinguish from cobalt blue...


                        Sure, but don't inks mix differently than paints, inks being transparent and paints being opaque?

                        -Stu
                        • 9. Re: RGB or RYB?
                          CShockr
                          It's the difference between ink and paint....there is truly no "opaque white ink" white depends on the opacity and brightness of the substrate you are printing on. In printing, you subtract ink to get white (paper). When printing ink on paper, you have to take in the substrate's brightness, coating, and opacity to determine how bright or dull your ink will actually print. Very bright colors can appear dull on non-coated stock (due to dot gain and lack of coating forcing the ink to form a true drop). Also, all of the inks, are transparent, even black, so you rarely can generate a true solid black without mixing in some cyan, magenta or even possibly yellow.

                          The cyan used in printing is not as pure as it should be that is why when you are determining aimpoints for pre-press, you generally have to bump the cyan up by 20% over the magenta and yellow inks, even in the neutrals.

                          A good "rich black" may actually have a reading of C40 M20 Y0 K100. If you run C0 M0 Y0 K100 you will get a charcoal color because of the transparency of black ink....

                          There is a lot more to it than this, but yes, a cobalt blue can be established from cyan and magenta inks...by an excellent pressman on an excellent press.

                          But I would rather use Pantone Reflex Blue to ensure quality and coverage on press...(that's why Pantones were created...to ensure quality color across a run when you have so many factors to control...)
                          • 10. Re: RGB or RYB?
                            PECourtejoie Adobe Community Professional
                            Hello, Stu!
                            I thought that you'd ask for 32 bits support, if it is not yet done ;)
                            • 11. Re: RGB or RYB?
                              agbanks Level 1
                              I know I'm a bit late weighing in on this one, but I've done a bit of work on colour wheels (partly while researching this book) and I have to agree that alternative colour wheels would be a good feature. Color Consultant Pro would be quite a good example to follow. Chris is correct in saying that almost the whole tradition of colour theory in art is superseded by what we now know of the physics and neurology, and kuler is presumably not aimed primarily (ho ho) at people who are mixing real paint. But it's interesting to look at what a traditional artist would have thought were complements, as well as accurate complements.

                              It seems to me even more important to have a smarter approach to CMYK (I note the Color Spaces thread). Beyond switching profiles, wouldn't this be a great opportunity to develop a custom algorithm to normalise CMYK values in colour harmonies? Giving deep blue as 96,96,0,30 is pretty useless, for example.

                              I'll stop now before I mention hexachrome and get flamed :-)