How many primary colors?

[joseph_wisniewski]

<p>Bruce, you're quite welcome...</p>

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<p>I have concluded that we are more advanced than monkeys because we have the ability to destroy our planet and they do not.</p>

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<p>That reminds me of Douglas Adams</p>

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<p>man had always assumed that he was more intelligent than dolphins because he had achieved so much - the wheel, New York, wars and so on - whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man - for precisely the same reasons.</p>

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[JDMvW]

<p>Just a sort of editorial note. Sometimes these threads that wander off into physics and such-like things can be a little frustrating, but mostly they are a pure joy. They have a tendency to veer toward metaphysics as well as physics, and there's a wonderful koan quality to them - "What is the color of one primary being sensed?".</p>

<p>By the end of one of these, one often isn't sure whether there is an objective reality at all, but everyone has had a nice mental workout, and -- most important of all -- everyone is leaving more confused than when they started. ;)</p>

[Alan Marcus]

<p >First I stand pat on my statement that when blending water colors, the greatest variety of hues will be produced by blending three primaries commonly called “red”, “blue” and yellow. The red however will really be a red-blue known as magenta and the blue will really be blue-green known as cyan. Cyan, magenta, and yellow are called subtractive primaries because each reflects about 2/3 of the white light energy that plays on them and each absorbs about 1/3. Cyan absorbs red, and reflects green and blue. Magenta absorbs green and reflects red and blue. Yellow absorbs blue and reflects red and green. In other words the subtractive primaries selectively absorb one of the primaries and reflect away two of the primaries. If you disregard the word subtractive you can, in this framework, proclaim that there are 6 primaries.</p>

<p > </p>

<p >Indeed the Sharp 5 primary LCD TV system to be introduced consists of red, green, blue, cyan and yellow. Now TV, an additive system depends on good and efficient filters. Sorry to report we have never been able to make good red, green and blue filters. The red filter should pass only red and block green and blue. To accomplish this it must be quite dense. So dense in fact, that its filter factor is shockingly high. Same is true for the other two primary filters. Green should only pass green and blue should only pass blue. Likely Sharp will use cyan to improve green and blue transmission by suppressing red. Likewise, yellow will improve red and green transmission while controlling blue (I am guessing but I’ll bet I am right). </p>

<p > </p>

<p >Color films and digital chips record the world based on sensitivities to the three additive primaries red, green, and blue. First color photograph ever 1861 used three projectors (black & white lantern slides) red, green, blue filters. First subtractive color system 1868 C. Cross. Three color carbon print 1877. G. Lippmann color photography, no dyes of any color, by interference (magnificent but impractical) 1881. Louis Ducos Du Hauron. A. Lumiere 1907 Autochrome red, green, blue starch grains as filters. L. Gaumont three color additive cinematography 1912. Kodak two color Kodachrome subtractive 1914. Technicolor two primary process 1915. Kodak Lenticular Kodacolor additive 1928. Technical three primary process 1930. Mannes, Godowsky 1935 three color subtractive Kodachrome. Dr. Land (Polaroid) demonstrated two color theory 1959, no commercial application. </p>

<p > </p>

<p >Now color film, both slide (positive) and color negative display cyan, magenta, and yellow dye images as do color prints on photographic paper. Ink and dye based prints on paper also image via the subtractive primaries plus the key color black.</p>

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<p >The human response to color is complex. We are dealing with light stimulus to the retina that communicates to the brain via a complex network of nerves. Many theories regarding vision have come and gone. All fall short as to a satisfactory explanation. The latest is electrical stimulation via a digital camera in a pattern, on the tongue stimulates the visual cortex allowing the blind to see (this is extraordinary and miraculous). Now we can conclude human color vision is more complex than separate sensitivity for each wave length. How we see and how we perceive colors has not yet been answered. </p>

[mrstubbs]

<p>There be warm.. and cool ..and neutral where combined equally.<br>

Warm is red ..Cool is cyan.<br>

Red comes where yellow and magenta are equally portioned. Cyan, as from green and blue.</p><div></div>

[yog_sothoth]

<p>I always wondered about the three color thing until I learned about the human eye and their three-color sensitivity. Do Birds sensitive to four frequencies looking at a computer screen get a headache? There is a proposal idea in there somewhere. </p>

<p>The sun emits mostly green light, so our eyes are optimized to see green +/- some scatter. If you try to see too many wavelengths you likely get into grief with trying to focus all of the wavelengths with one lens.</p>

<p>In any case electromagnetic radiation doesn't care what we think, it exists in continuous wavelengths ranging from huge to very tiny and has nothing physically tying it to any "primary" wavelengths.</p>

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[charlesheckel]

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<p>The whole concept of their being as many primary colors as there are types of photoreceptors in the eye is pure bunk. --Joseph Wisniewski</p>

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<p>In the human eye, there are three types of color photoreceptors. Human eyes are trichromic and see three primary colors. Three equals three.</p>

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<p>everyone is leaving more confused than when they started. ;) --JDM Von Weinberg</p>

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[joseph_wisniewski]

<p>Charles, I and others were clear enough on this. It is not possible to pick three sources of light (even monochromatic lasers) that you can add to make all the colors the eye can see. It is not possible to formulate three paints or three dyes that can be mixed to produce all the colors the eye can see.</p>

<p>Three apples <strong>does not equal</strong> three oranges.</p>