posted
So, in high school science classes, I was taught to understand color in two ways. One was a linear spectrum, bounded on one side by infrared, and on the other side by ultraviolet. The other was a continuous wheel with opposing colors, which explained the interaction of different colored lights and pigments.
Do these two models seem incompatible to anyone else? I mean, an object that reflects both red and green light looks yellow, because yellow is between red and green on the spectrum ... but an object that reflects both red and blue light look purple, even though purple is even further down the spectrum from blue? The rules of combining colors of light and pigments are consistent on the wheel, but seem coutnerintuitive on the spectrum, yet the spectrum is what connects these rules to our larger understanding of electromagnetic waves.
So, how do these two seemingly-incompatible models fit together?
Posts: 1907 | Registered: Feb 2000
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posted
All I know is that when you add two frequencies together, you don't always (or maybe ever) get a frequency that's in between the two. Of course, I don't remember how to add frequencies together, so I don't know how helpful this answer is.
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posted
The wheel is actually a solid that is kind of shaped like a mango. So you have the color wheel, that you are familiar with, being the circumference of the mango. Then one tip of the mango is light and the other end is dark. The light tip extends furthest in the yellow segment of the circumference. The dark end extends at the purple.
But in terms of the spectrum, you are probably aware that it corresponds with a frequency of energy that can be expressed as a number. The idea that long red waves can be blended with short blue waves to produce purple is an effect of the frequency that appears as a combination/interference of the two waves, and is probably shorter even than the blue. All the waves put together make white, because it's just a mess.
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The color wheel for subtractive color mixing is intended for compositional and pigment (subtractive) color theory, which really has little to do with actual physics, and much more to do with aesthetics.
It is only this wheel of the two cases that I feel qualified to discuss. We did cover it rather exhaustively in Design and Color. (I was an Art Major...).
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posted
Like eslaine said, the Wheel approach accomodates the peculiar engineering of the eye, whereas the Spectrum approach is more directly related to wavelength of EM, of which visible light is a tiny subset.
posted
Ah, the primary colors of pigments: one of the great lies of elementary school, ranking right up there with the long/short vowel distinction.
Red, yellow, and blue do not work well as primary colors of pigments. Cyan, magenta, and yellow (the secondary colors of the additive system) DO make good primary colors of pigments. Why do you think that's what printers use?
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posted
Yeah, and fluorescence image processing is in an RGB system because our eyes have red, green and blue detectors.
Isn't it a delightful mess?
I'm glad I only have to deal with the spectral relations. You know, aside from that one week a year I paint (next week!). I only have to care about ranges of emission bands. I can capture blue and make it green! Muahahahaha!
Edit: so what word should I have used? I had color, but I thought that was too confusing.
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I have recently noticed that myself, Jon Boy. It always bothered me how the "secondary" colors that came from mixing the supposed pigment primary colors were ugly and muddy at best. But if you use cyan, magenta, and yellow as your primaries of pigment, the secondaries come out bright and beautiful!
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posted
The reasons that colors and mixing colors is so weird is because of how our eyes work. Our eyes can only pick up the intensities of Red, Green, and Blue. We cannot distinguish the difference between light that is yellow and light that is red mixed with green. There is a difference in the light waves -- one is comprised of all one frequency and the other has half of one and half of the other.
On a related note, there are studies that indicate the existence tetra chromats who can percieve color through four different colors -- Red, Green1, Green2, Blue, IIRC. Two colors that would look identical to us could look different to them.
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posted
By the way, I do know the difference between light colors and pigment colors. My question was more about the interaction between the two models, both of which are applied to light colors, but both of which seem to contradict each otehr.
I think mr_port might have hit it on the head there ... that the wheel model is a function of the way our eyes work, and is not a function of the actual progression of frequencies.
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quote: Ah, the primary colors of pigments: one of the great lies of elementary school, ranking right up there with the long/short vowel distinction.
Red, yellow, and blue do not work well as primary colors of pigments. Cyan, magenta, and yellow (the secondary colors of the additive system) DO make good primary colors of pigments. Why do you think that's what printers use?
I agree. But if you mix paints, try the subtractive primaries. Otherwise you will end up with brown. I do love the idea of additive color mixing, and have had practical experience in both printing design and lighting design for theater using additive primaries. What really becomes strange is when you are trying to mix the two theories, i.e. paint on your set is mixed in subtractive primaries, and the lights are additive. The additive primary hits a subtractive color and you get strange results, sometimes very counterintuitive.
But subtractive color is merely a theory of removing colors. Additive color is what we deal with more in everyday life, but less people know how it works. That's what I could never understand. I would talk about green and red mixing to become yellow (additive theory) and that's where I would lose people.
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posted
I'm a little lost, eslaine. What are you calling the subtractive primaries? Red, yellow, and blue, or magenta, yellow, and cyan?
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I have to say that I kinda felt like this thread validated my existence on hatrack. The Dog liked my post! I have value! I can now pour all of my self worth into hatrack!
I try to avoid being a fanboy, but sometimes I just can't help it.
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The subtractive primaries are Red, Yellow and Blue. The additive primaries are Red, Green and Blue. People like to use the actual names of the colors that are closer to the actual wavelength (i.e. magenta and cyan), but if you mix paint, Red/Yellow/Blue, if you are mixing spotlights Red/Blue/Green.
Light in physics, in my opinion, is best described by the spectrum, not the wheel. After all, beyond violet is ultraviolet, before red is infrared. Subtractive mixing (Red, Yellow, Blue) is only helpful in describing how colors will mix, and how the human mind will react aesthetically to them in combination (mono-, bi-, and tri-chromatic compositions are examples that use the color wheel.) The reason that I don't trust the color wheel, is that I've seen competant artists get away with color compositions that are not derived from the color wheel and "color theory". This leads me to believe that the color wheel is merely a guide only.
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...this explains why the people at the newspaper yelled at me when I sent an ad to be published in RGB format. It's all slowly making sense....
Posts: 8504 | Registered: Aug 1999
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Spectrum--Wheel--I think they are both wrong. I see color as more of an inverse dodecahedron that slowly spins counter intuitevly along 4 of it axis while mainting relative static to its intra and inter-dimmensional phases.
But then again, the sky is a light orange with plaid poka dots in my Universe.
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The really strange thing here is that when we ressurect this thread in five years (how, I don't know... ) and it will have been discovered that Dan was right....
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quote:The subtractive primaries are Red, Yellow and Blue.
No, they aren't. That's what I'm saying. The subtractive primaries are cyan, magenta, and yellow. The subtractive secondaries are red, green, and blue. The problem is that it's hard to find good cyan and magenta paint.
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