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Is there any evidence that RYB is more than a historical mistake which our culture has been slow to grow out of? We know now that the correct subtractive primar

Is there any evidence that RYB is more than a historical mistake which our culture has been slow to grow out of? We know now that the correct subtractive primary colors are CMY. Your informal experiments with art students may speak more to how they were (mis)educated than to anything intrinsic about color perception, no?

Daub 6y ago
A good question. The disputable value is 'maximum possible perceptual hue difference'. In color science, difference is usually understood in terms of 'minimum possible'. This is how the god-like Albert Munsell first mapped the perceptual color domain. Maximum possible has almost no presence in color science literature. I assume that this is because of the asymmetry of perceptual maximum/perceptual minimum. Without solid empirical data, I can only support the validity of RYB pairs by pointing out that Leonardo (and everyone else who wrote about color prior to Newton), supported this pairing without knowing the relative position of these pairs on any color wheel. A weak argument, perhaps. I know it is possible to design an experiment to prove/disprove the validity of RYB complementaries. It was on our to-do list before our computational aesthetics project ran out of money. However, I shall continue to assume its truth. My reason is simple: from a life time as a painter I know that RYB complementary pairs are true. An even weaker argument.
tobr 6y ago
Our understanding and interpretation of colors are very much shaped by the culture, such as which words we have to describe colors. So can you really say that it would amount to miseducation, just because it doesn’t fit color perception perfectly?
klodolph 6y ago
The idea that RYB is somehow a mistake is a difficult one to defend. > We know now that the correct subtractive primary colors are CMY. It is not that simple. CMY is not "correct" by any sense of the word. Both additive and subtractive color models suffer from the same flaw... you cannot represent all perceptible colors by starting with three colors and mixing them. CMY is simply a choice from one of many possible choices. CMY and RGB are both simply convenient choices. By choosing RGB primaries (and there are a lot of different reds, greens, and blues to choose from) you can represent a reasonably large subset of the colors present in the natural world. However, if create a monochromatic (narrow band of wavelengths) light source which looks yellow, you won't be able to reproduce that color of yellow by mixing red and green. There are experiments that test exactly this property. RGB is limited. In a sense, the choice of red, green, and blue is arbitrary. The primary colors are not derived from some property of physical light, nor are they derived from some truth about human color perception. They do happen to work very well--because the space of colors we can perceive is vaguely triangular. There are consumer printers you can buy that go well beyond simply CMY or CMYK color models. Epson sells printers with six colors of ink, not counting black. Commercial printing services also provide "spot" channels for whatever color of ink you are able to source.
- zokier 6y ago
  > In a sense, the choice of red, green, and blue is arbitrary. The primary colors are not derived from some property of physical light, nor are they derived from some truth about human color perception. What about the cone cell response curves which roughly correspond to r, g, and b? https://commons.m.wikimedia.org/wiki/File:Cones_SMJ2_E.svg#mw-jump-to-license https://commons.m.wikimedia.org/wiki/File:Cones_SMJ2_E.svg#m... > They do happen to work very well--because the space of colors we can perceive is vaguely triangular. That is hardly a coincidence. Our perceived color space is vaguely triangular because we have vaguely three types of cone cells to detect color.
  - klodolph 6y ago
    > What about the cone cell response curves which roughly correspond to r, g, and b? The diagram is misleading because the spectral sensitivity curves are drawn using red, green, and blue colors on the chart. Read the wavelengths on the bottom--they do not roughly correspond to red, green, and blue. This is why they are named L, M, and S instead. The peak sensitivities are closer to green, a different green, and violet. > That is hardly a coincidence. Our perceived color space is vaguely triangular because we have vaguely three types of cone cells to detect color. It's a poor approximation of a triangle. It's more paraboloid. It would be a triangle if there were no overlap between the spectral sensitivity of different receptors. Since there is overlap between the green, other green, and purple receptors, the shape is not a triangle.
    - tobr 6y ago
      > The peak sensitivities are closer to green, a different green, and violet. This is fascinating. My first instinct is to say that the peak of those curves are not as important as where they discriminate best/where they are most different from the other curves - which does seem to give a more clear red, green and blue. But I’m sure it’s not that simple when you take into account how the brain processes these signals. Would it be possible to create a good color screen using subpixels emitting light at the peak sensitivity frequencies?

Daub 6y ago

A good question. The disputable value is 'maximum possible perceptual hue difference'. In color science, difference is usually understood in terms of 'minimum possible'. This is how the god-like Albert Munsell first mapped the perceptual color domain. Maximum possible has almost no presence in color science literature. I assume that this is because of the asymmetry of perceptual maximum/perceptual minimum. Without solid empirical data, I can only support the validity of RYB pairs by pointing out that Leonardo (and everyone else who wrote about color prior to Newton), supported this pairing without knowing the relative position of these pairs on any color wheel. A weak argument, perhaps. I know it is possible to design an experiment to prove/disprove the validity of RYB complementaries. It was on our to-do list before our computational aesthetics project ran out of money. However, I shall continue to assume its truth. My reason is simple: from a life time as a painter I know that RYB complementary pairs are true. An even weaker argument.

tobr 6y ago

Our understanding and interpretation of colors are very much shaped by the culture, such as which words we have to describe colors. So can you really say that it would amount to miseducation, just because it doesn’t fit color perception perfectly?

klodolph 6y ago

The idea that RYB is somehow a mistake is a difficult one to defend. > We know now that the correct subtractive primary colors are CMY. It is not that simple. CMY is not "correct" by any sense of the word. Both additive and subtractive color models suffer from the same flaw... you cannot represent all perceptible colors by starting with three colors and mixing them. CMY is simply a choice from one of many possible choices. CMY and RGB are both simply convenient choices. By choosing RGB primaries (and there are a lot of different reds, greens, and blues to choose from) you can represent a reasonably large subset of the colors present in the natural world. However, if create a monochromatic (narrow band of wavelengths) light source which looks yellow, you won't be able to reproduce that color of yellow by mixing red and green. There are experiments that test exactly this property. RGB is limited. In a sense, the choice of red, green, and blue is arbitrary. The primary colors are not derived from some property of physical light, nor are they derived from some truth about human color perception. They do happen to work very well--because the space of colors we can perceive is vaguely triangular. There are consumer printers you can buy that go well beyond simply CMY or CMYK color models. Epson sells printers with six colors of ink, not counting black. Commercial printing services also provide "spot" channels for whatever color of ink you are able to source.

zokier 6y ago
> In a sense, the choice of red, green, and blue is arbitrary. The primary colors are not derived from some property of physical light, nor are they derived from some truth about human color perception. What about the cone cell response curves which roughly correspond to r, g, and b? https://commons.m.wikimedia.org/wiki/File:Cones_SMJ2_E.svg#mw-jump-to-license https://commons.m.wikimedia.org/wiki/File:Cones_SMJ2_E.svg#m... > They do happen to work very well--because the space of colors we can perceive is vaguely triangular. That is hardly a coincidence. Our perceived color space is vaguely triangular because we have vaguely three types of cone cells to detect color.
- klodolph 6y ago
  > What about the cone cell response curves which roughly correspond to r, g, and b? The diagram is misleading because the spectral sensitivity curves are drawn using red, green, and blue colors on the chart. Read the wavelengths on the bottom--they do not roughly correspond to red, green, and blue. This is why they are named L, M, and S instead. The peak sensitivities are closer to green, a different green, and violet. > That is hardly a coincidence. Our perceived color space is vaguely triangular because we have vaguely three types of cone cells to detect color. It's a poor approximation of a triangle. It's more paraboloid. It would be a triangle if there were no overlap between the spectral sensitivity of different receptors. Since there is overlap between the green, other green, and purple receptors, the shape is not a triangle.
  - tobr 6y ago
    > The peak sensitivities are closer to green, a different green, and violet. This is fascinating. My first instinct is to say that the peak of those curves are not as important as where they discriminate best/where they are most different from the other curves - which does seem to give a more clear red, green and blue. But I’m sure it’s not that simple when you take into account how the brain processes these signals. Would it be possible to create a good color screen using subpixels emitting light at the peak sensitivity frequencies?