This article tries to sensationalize and obfuscate something that is pretty simple in reality.
RGB are the primaries in light. By mixing these three colors you can create any color the human vision system can perceive (yes, because of tristimulus).
When white light hits a material, some of those RGB wavelengths are absorbed (subtracted). RGB - GB(Cyan) = Red, RGB - RG(Yellow) = Blue, RGB - RB(Magenta) = Green. Thus, Cyan, Magenta and Yellow act as primaries (colors from which you can construct any visible color) for materials that absorb, not emit light.
The forth primary in print media, Black, is simply added because inks are imperfect and a mix of CMY inks yields a kind of murky black (plus it wastes ink).
It's a historical simplification to say that "red, yellow and blue" are the primaries for paint, the red works like a magenta, the blue works like a cyan. They sell Cyan/Yellow/Magenta primaries for oil/acrylics and if you paint with these you'll get a brighter, wider palette but you can get there with a traditional palette by adding whites and other pigments.
The tone of the article is awful. The opening sentence, "Ask any artist..." is flatly untrue, this stuff is basic for most visual artists (I first learned about the CMY primaries in a community ed. Painting I class). It's not that the article is factually wrong, it's just basic stuff presented as if it were obscure or clever.
None of this makes the color wheel or any other color theory any less valid. The "four color" wheel he lists at the end is not wrong, it's just silly: you could pick any points on the wheel and their opposites and have the same thing.
This isn't correct. The color space is horseshoe-shaped and cannot be represented by a triangle of three additive primary colors. In addition, standard color gamuts tend to be quite a bit smaller than theoretically possible. Check out: https://secure.wikimedia.org/wikipedia/en/wiki/Gamut . This is why hi-def TV is defining extensions to the usual colorspace.
Furthermore, the laws of physics don't particularly care that humans perceive three color dimensions, and surfaces and lights are allowed to absorb or emit whatever wavelengths they please. When you have a light source with a funky spectrum, this can cause colors to look very strange, as a surface might not reflect a funny, spiky spectrum the same way (w.r.t. the human 3-dimensional color space) it will reflect a smooth color spectrum of the same color. You've probably seen cars seemingly change color when the light source is primarily those orange-ish streetlights. My parents' red minivan, for instance, turns a red-tinted grey.
Sorry to disappoint you, but color theory is in fact anything BUT simple. For starters, RGB are not "THE primaries in light." In fact, primary colors aren't a property of light but of the way you perceive light. You could just as successfully choose a different set of 3 primary colors and still be able to represent [an approximation of] any other color. That is, of course, assuming you're trying to represent color to a human with 3 types of cone cells - otherwise things only get more complicated...
I think you're right in some respects (e.g. most artists have a much more sophisticated understanding of color than red, yellow, blue -- that's the version you get taught in elementary school).
But you're missing the point in others: half the article is devoted to explaining the inadequacies of the RGB model for handling actual real world color. (This is why photos of sunsets -- digital or film -- never look right.)
A simple example -- color looks weird under "white" LEDs (at least the current ones) because they're actually RGB LEDs balanced to create the illusion of "white" light. Some orange things will look all but black under a white LED while others will look orange. Why? Because orange light can be actually orange, or a mixture of wavelengths that gets a similar response from your eye.
And so on and on. The article is a bit annoying (and it would help if it assumed most readers will know about CMYK and RGB color models already) but the fundamental lesson -- that color is more complex than you think and you need to understand the underlying physics and physiology to really understand color is worth making.
> This is why photos of sunsets -- digital or film -- never look right
The main reason sunsets don’t look right is that sunsets have a huge dynamic range, beyond the ability of our printed photographs or computer displays to reproduce (no one has the sun in their living room).
No, the main reason is that RGB is an approximation of color not true color. Light in the real world isn't RGB. Human beings do not see in RGB. Read the damn article. (There's also a lengthy post above which tries to make the points over again.)
Do you think CMYK will reproduce sunsets if you shine a bright enough light on a piece of paper and use black enough ink? Same argument.
I understand the concept of metamerism. You are quite right about objects changing appearance from one light source to the next, etc. It’s also true that sunsets often have colors which are more colorful than can be produced by computer displays or 4-color-process prints. However, I stand by my assertion that the main reason that sunsets don’t look right on screen or in print has to do with the lack of dynamic range.
Can you explain why your statement "pretty simple... RGB are the primaries in light" is true, his explanation in his article "complex... RGB is just a rough approximation" is false? He gives a plausible physiological explanation.
It’s not that simple: explaining it properly takes dozens if not hundreds of pages.
> RGB are the primaries in light.
This depends on what you mean by “primaries”. As far as I can tell, your definition is based on common color reproduction technologies, rather than the physiology of human visual perception. That’s fine, but recognize then that the “primaries” chosen for practical use are constrained by economic factors, &c. The three best lights for additive color reproduction are indeed R (an orangish red color), G (a yellowish green), and B (a blue-violet color): this is because those are the colors which maximize the differential responses of different cone cells, as can be seen in this diagram in Hunt’s book The Reproduction of Colour: http://i.imgur.com/ZOdZc.png Of course, such narrow-spectrum sources are not economically/technically feasible, and so instead a typical computer or television uses lights like these: http://i.imgur.com/JHeGa.png By contrast, a typical subtractive system uses primary dyes like these: http://i.imgur.com/qri1f.png (the colored lines on the charts are the reflectances at various concentrations)
You cannot reproduce any color the human visual system can perceive through just three primary lights: every display system has a “gamut”, and for example computer displays have great difficulty displaying saturated blue-green colors.
As Hunt summarizes,
“It will be realized that these three expedients cannot correct for the fundamental limitations of the process, which spring from the nature of the colour mechanism of the eye and the shape of the spectral absorption curves of the best available cyan, magenta, and yellow dyes. What is claimed for modern subtractive processes is that they produce pleasing colour pictures, and that the inevitable inaccuracies are balanced in such a way as to be least noticeable.”
> The "four color" wheel he lists at the end is not wrong, it's just silly: you could pick any points on the wheel and their opposites and have the same thing.
This is not true. Color opponency and the specialness of the so-called “unique hues” have had a great deal of scientific literature about them (physiology, psychophysics, linguistics, etc.), and no, you could not just pick any four arbitrary points. Of course, there’s some learned/cultural component to people’s color categorization too, and there are individual physiological differences, so there’s inter-observer disagreement on precisely what color is “unique red”, etc. But it is indeed true that any color can be described as some combination of red, yellow, blue, green, white, and black: this is Hering’s theory of color vision, the inspiration for the Swedish NCS system, based on decades of rigorous measurements in the 40s–70s.
The current scientific consensus is that color vision can be modeled in a simple way with 2 stages: (1) trichromacy of 3 cone responses, (2) higher-level opponent mechanism. There are many more complicated effects beyond that, and it’s essential to consider adaptation, but those 2 cover the basics.
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All of that said, I’m not completely satisfied with the original essay either. It’s pretty fluffy and hand-wavey, and the jokey language gets in the way. Conflating long/medium/short cones with red/green/blue colors is dangerous because it hides what’s really going on. I wouldn’t, as the author of this article does, call the red–yellow–blue–green anchored hue circle “proper”; there are other equally valid organizations, such as the Munsell system’s, which aims for perceptually uniform hue spacing.
Still, on the whole it’s on the right track.
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I’m sorry that the Wikipedia articles about these topics aren’t clearer and more comprehensive, or I’d point you there. As the article says, the best resource online is Bruce MacEvoy’s handprint.com, but several books have excellent explanations. If you’re interested and MacEvoy’s site doesn’t clear things up I can suggest where to look in the library.
The content of the article is a fine introduction for the layman, which is framed with the stupid and condescending "Artists gets it wrong" angle.
It would be like an introduction to the web which begins "professional software developers believe that the internet is the same as the blue 'e' icon on the desktop, but actually..." No, software developers does not believe that, but the layman reader may.
Btw. I disagree that mixing primary inks yield brown because inks are imperfect. Rather, brown is the color you would expect according to theory, because mixing pigments should average their effect.
You said it with more finesse, but exactly. This is just an badly written article on a subject that is clearly not understood by the author trying to grab eyeballs through sensationalism.
Using printer inks as an example was the first big cue that this was link bait to a self-aggrandizing blog.
RGB are the primaries in light. By mixing these three colors you can create any color the human vision system can perceive (yes, because of tristimulus).
When white light hits a material, some of those RGB wavelengths are absorbed (subtracted). RGB - GB(Cyan) = Red, RGB - RG(Yellow) = Blue, RGB - RB(Magenta) = Green. Thus, Cyan, Magenta and Yellow act as primaries (colors from which you can construct any visible color) for materials that absorb, not emit light.
The forth primary in print media, Black, is simply added because inks are imperfect and a mix of CMY inks yields a kind of murky black (plus it wastes ink).
It's a historical simplification to say that "red, yellow and blue" are the primaries for paint, the red works like a magenta, the blue works like a cyan. They sell Cyan/Yellow/Magenta primaries for oil/acrylics and if you paint with these you'll get a brighter, wider palette but you can get there with a traditional palette by adding whites and other pigments.
The tone of the article is awful. The opening sentence, "Ask any artist..." is flatly untrue, this stuff is basic for most visual artists (I first learned about the CMY primaries in a community ed. Painting I class). It's not that the article is factually wrong, it's just basic stuff presented as if it were obscure or clever.
None of this makes the color wheel or any other color theory any less valid. The "four color" wheel he lists at the end is not wrong, it's just silly: you could pick any points on the wheel and their opposites and have the same thing.