Color: Physics and Perception?

#1
It’s easy to understand how matter such as objects, paints, filters, etc. can absorb photons or for instance how a polaroid material can selectively absorb light from one plain, typically transmitting less than 1% through a sheet of polaroid, while transmitting more than 80% of light in the perpendicular plane. But when it comes to light itself, the subtractive theory of color, i.e. absorption, doesn’t make sense at all.

Excerpt from video--->Colour Mixing
I’ve always had a problem with color mixing because I know that you can’t mix photons together. So, you can’t take a blue photon and a green photon and mix them together to get some other photon. That just doesn’t happen. Color mixing is definitely something that you can do. Well, actually, you can’t mix colors in physics, but you can do it in biology. It’s to do with how your eyes work. For example, if I shine red and green light into your eyes and overlap them, you will see yellow. If you mix two colors together, you get the color in between on the color spectrum. We can test that again by looking at green and blue together. If I mix green and blue, I get cyan and cyan is between blue and green on the spectrum. But why, why is that? Well, your eyes can’t measure the wavelength of light directly. Instead, you have these cone cells that are sensitive to the different parts of the spectrum. You’ve got red cones, blue cones and green cones. What about yellow? You don’t have a yellow cone. Yellow is close to red so your red cone fires a bit and yellow is close to green so your green cone fires. So, your brain is getting a message form your red and green cones at the same time and deciding that I must be looking at something in between those two colors then. So, that is brilliant because your brain is perceiving something about the world that it isn’t able to directly measure. But that does mean it can be tricked. So, what about magenta? Well, what should your brain do if your red cone fires and your blue cone fires but your green cone doesn’t fire? Does it do the same thing? Does it think I must be looking at something in between red and blue? But the color in between red and blue is green and you’re definitely not looking at something green because your green cone isn’t firing. So, in this situation, your brain invents a color. It makes up a color and that color is magenta. You don’t see magenta in the rainbow because it doesn’t have a wavelength.

You don't have to use a filter or colored filtered flashlights. You can see that the same thing applies when using just sunlight and a prism and we know that a prism doesn't absorb light. You can see that if you take the secondary colors (yellow, magenta, cyan), which some refer to as rays of shadows or Goethe spectrum vs. Newton spectrum, and try to isolate any one of them, they split into two primary colors. The cyan splits into blue and green. Magenta splits into red and blue and the yellow splits into red and green. 


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It’s common knowledge that when you mix red, blue and green together, you get white light. When you mix cyan, yellow and magenta, you get black. Yellow absorbs the blue light, magenta absorbs the green light and cyan absorbs the red light. With all the light absorbed, we see black. They say that white light minus blue, green and red light is no light at all, but technically the spectrum is still present, which is a little confusing. When it comes to light itself, what do they mean by absorbed because photons don’t absorb other photons?

From what I’ve read, it looks like photons don’t really cancel each other out either. Take the double slit experiment for example, destructive interference would violate the law of conservation of energy. It’s conserved in the superposition of waves. It’s not destroyed at the points of destructive interference and created at the points of constructive inference; it is redistributed in space. The energy is transferred from the region of destructive interference to the region of constructive interference.


https://www.youtube.com/watch?v=Iuv6hY6zsd0


So, when it comes to light, there’s really no absorption going on at all, right? Is this all just simply our biological perception of light?
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#2
(Nov 25, 2019 07:53 PM)Secular Sanity Wrote: So, when it comes to light, there’s really no absorption going on at all, right? Is this all just simply our biological perception of light?


Yah, not the EM activity itself minus atoms. Since printing (and painting) depend upon reflected light ("reflected" being figuratively quick but overly simplistic), it's the chemicals constituting the inks and pigments that do the absorbing and selective "re-emitting" of certain wavelengths. But those substances don't have perfectly desired properties (it may also have to do with how they're distributed on a surface), so other frequencies of the visible light spectrum are not totally absent in terms of what reaches the eyes from them (even if they're usually too weak to register). So despite theory, equal amounts of intermingled cyan, magenta, and yellow inks fail to actually yield an ideal black or to accomplish complete absorption (the printing process, of course, compensating by adding black ink dots).
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#3
(Nov 26, 2019 12:01 AM)C C Wrote:
(Nov 25, 2019 07:53 PM)Secular Sanity Wrote: So, when it comes to light, there’s really no absorption going on at all, right? Is this all just simply our biological perception of light?


Yah, not the EM activity itself minus atoms. Since printing (and painting) depend upon reflected light ("reflected" being figuratively quick but overly simplistic), it's the chemicals constituting the inks and pigments that do the absorbing and selective "re-emitting" of certain wavelengths. But those substances don't have perfectly desired properties (it may also have to do with how they're distributed on a surface), so other frequencies of the visible light spectrum are not totally absent in terms of what reaches the eyes from them (even if they're usually too weak to register). So despite theory, equal amounts of intermingled cyan, magenta, and yellow inks fail to actually yield an ideal black or to accomplish complete absorption (the printing process, of course, compensating by adding black ink dots).

Maybe I’m thinking about this all wrong or missing something. It's easy to understand how the additive color theory works with our cones but not the subtractive theory if nothing is being absorbed.

In physics, black is the absorption of all colors when no visible light reaches the eye. If the light isn’t being absorbed, how does the combination of colors cause our eyes to see black?

I just don't get it.  Undecided
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#4
(Nov 26, 2019 03:52 AM)Secular Sanity Wrote:
(Nov 26, 2019 12:01 AM)C C Wrote:
(Nov 25, 2019 07:53 PM)Secular Sanity Wrote: So, when it comes to light, there’s really no absorption going on at all, right? Is this all just simply our biological perception of light?

Yah, not the EM activity itself minus atoms. Since printing (and painting) depend upon reflected light ("reflected" being figuratively quick but overly simplistic), it's the chemicals constituting the inks and pigments that do the absorbing and selective "re-emitting" of certain wavelengths. But those substances don't have perfectly desired properties (it may also have to do with how they're distributed on a surface), so other frequencies of the visible light spectrum are not totally absent in terms of what reaches the eyes from them (even if they're usually too weak to register). So despite theory, equal amounts of intermingled cyan, magenta, and yellow inks fail to actually yield an ideal black or to accomplish complete absorption (the printing process, of course, compensating by adding black ink dots).

Maybe I’m thinking about this all wrong or missing something. It's easy to understand how the additive color theory works with our cones but not the subtractive theory if nothing is being absorbed.

In physics, black is the absorption of all colors when no visible light reaches the eye. If the light isn’t being absorbed, how does the combination of colors cause our eyes to see black?

[...] I just don't get it.  Undecided


I'm editing this yet again to go through the following first, before the diagram. Hopefully I haven't scrambled it somewhere, because I've been repeatedly interrupted even at this hour (Thanksgiving week and all that Dodgy):

This also probably needs to be gotten out of the way, which someone hypothetically might ask: Why do CMY colors absorb their opposite colors of RGB? It's actually due to the chemical properties of the ink, quasi-transparent filter material, etc rather than the EM waves of visible light range or the experience of color in the brain itself doing anything, that the substance has been conveniently labeled with name-wise. But we can forget that technical mess (this procession right here is potentially confusing enough).

White light = red, green, blue light in equal amounts. (RGB)

A printed dot of substance (ink, pigment) that looks cyan color when shining white light on it is absorbing (subtracting) red light and reflecting equal amounts of blue and green.

A printed dot of substance that looks magenta color when shining white light on it is absorbing (subtracting) green light and reflecting equal amounts of red and blue.

A dot of substance that looks yellow color when shining white light on it is absorbing (subtracting) blue light and reflecting equal amounts of red and green.

A combination of CMY printed dots of equal amount yields black (only in theory), because together they absorb all the RGB colors of white light.

Adding only two of the three subtractive CMY primaries together in equal amounts will produce one of the primary additive RGB colors via their combination eliminating two of the RGB colors. Example: Cyan (removes red) plus Magenta (removes green) equals blue remaining to reach the eyes.

Adding two or three of the CMY primaries together but in unequal amounts can produce various colors.

Here's a color absorption diagram below from a retail page, of all places. In the overprints section, for instance, you can see in the second horizontal row how a combination of cyan and yellow dots absorb their opposites of red and blue from white light, leaving only green to reach the eyes. I'll link to the diagram but if the image goes out it can be found here: https://www.xrite.com/blog/additive-subt...lor-models

Notice where there are all three CMY ink dots of equal size they do absorb the RGB primary colors to yield black (none are reflected back). But in practice the chemicals aren't perfect for accomplishing that, thus the addition of the fourth color (black itself) in CMYK to help absorb the lingering amount, etc. The fourth is supplied to enhance other subtractive color combinations, too.


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#5
(Nov 26, 2019 06:05 AM)C C Wrote: I'm editing this yet again to go through the following first, before the diagram. Hopefully I haven't scrambled it somewhere, because I've been repeatedly interrupted even at this hour (Thanksgiving week and all that Dodgy):

What was he thinking?
The year that is drawing toward its close has been filled with the blessings of fruitful fields and healthful skies. To these bounties, which are so constantly enjoyed that we are prone to forget the source from which they come, others have been added, which are of so extraordinary a nature that they cannot fail to penetrate and soften the heart which is habitually insensible to the ever-watchful providence of Almighty God.”—Lincoln
It doesn’t soften your heart when you’re the one preparing it and they’re still prone to forget the source. Dodgy

Don’t even think about it until after the holidays.

C C Wrote:This also probably needs to be gotten out of the way, which someone hypothetically might ask: Why do CMY colors absorb their opposite colors of RGB? It's actually due to the chemical properties of the ink, quasi-transparent filter material, etc rather than the EM waves of visible light range or the experience of color in the brain itself doing anything, that the substance has been conveniently labeled with name-wise. But we can forget that technical mess (this procession right here is potentially confusing enough).

And…that’s my point. I hate to drag you down a rabbit hole with me but I am getting curiouser and curiouser.

Here’s a video with Professor Phil Moriarty talking about transparency.

When it comes to transparent materials, the energy gap between the ground state and the excited level is so large that photons of visible light don’t have enough energy to jump to the next level and be absorbed. If they’re absorbed, the material is opaque and not transparent. The photons don’t make it through.

As I said earlier, this can be preformed with just a glass prism and sunlight. No filters, no ink, no substance and no chemical properties of any kind other than (nonabsorbent) transparent glass and light itself.


https://www.youtube.com/watch?v=_v2aJ96eX_8

Just think about that for a bit and then I’ll add a little in regards to polarization, interference and diffraction.


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Oh, and C C, I won’t be offended if you find it boring and want to tap out. No worries.
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#6
Okay, seizing a fleeting break from the holiday madness. Might be a couple of days before I visit Scivillage again.

Sorry, SS, but I'll probably have to drop out. Maybe it's due to family gathering distractions, but I still don't get what the issue even is in the thread when the latter shifts from CMY or CMYK subtractive model to prism effects, and items like what "absorb" was referring to in the OP if not the subtraction taking place by the chemicals in the inks, pigments. So clearly I just need to exit altogether since what problem the topic is specifically revolving around eludes me (I'm surely contributing obfuscation as a result of that).

However, there's that video in the OP of the guy talking about magenta being made up by the brain. The latter, of course, actually does that with the rest of the colors, too, but they have spectral coordinates to correspond to. The opposite or complementary color of green on the "color wheel" that both the additive RGB & subtractive CMY models use is "more invented" than the rest in that sense.

So how outlandish is it that a color like magenta can be recruited as a primary in a subtractive approach to color combination in printing, if it's not even a single wavelength or is "compound" or doesn't correspond to something definite/precise outside the head? For me, "magenta" is just a quick everyday label for the lengthy names of the chemicals used in the ink (etc). The substance does the actual absorbing of green (not the qualitative meaning of the color magenta), and then "reflects" red and blue wavelengths to reach the eyes and ultimately be construed by neural processes as the color "magenta".

Since white light itself is -- in a sense -- the ultimate "compound" visual phenomena with respect to it being split into a spectrum of colors by a prism, I don't initially deem it surprising if a blue/green color like cyan splits further into blue/green when passing through (if I'm even recalling that right from the OP in the midst of social chaos depriving attention here). Cyan does have spectral coordinates, whereas magenta as the odd child doesn't. But then again, there might be questions lingering over such and deeper matters to sort out. Or again, I'm still straying wide of the mark in terms of grazing what this thread is really about.
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#7
No worries, C C. I get it. Thanks for trying. 

Happy Thanksgiving!
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#8
(Nov 28, 2019 03:54 PM)C C Wrote: I still don't get what the issue even is in the thread when the latter shifts from CMY or CMYK subtractive model to prism effects, and items like what "absorb" was referring to in the OP if not the subtraction taking place by the chemicals in the inks, pigments. So clearly I just need to exit altogether since what problem the topic is specifically revolving around eludes me (I'm surely contributing obfuscation as a result of that).

By George, I think I’ve got it.

I'm just going to quickly explain, mostly as a note to self, in order to take advantage of Styrder’s (the keeper of good ideas) hospitality. Big Grin


https://www.youtube.com/watch?v=BVWYL9YVFFE

As it stands, the definition of the RGB additive model is mixing light, with all three, yielding white. The definition of the CMY subtractive model is color created by subtracting (absorbing) parts of the spectrum by the means of matter, such as pigments, dyes, ink, filters, etc. Absorption of all light (all colors) yields black.

I could be wrong but I don’t believe that there is a theory that explains how light interacts with itself to create a subtractive color model.

If you were to take any of the complimentary colors (CMY) and combined them, each color would still contain two components of the RBG spectrum. None of them would be absorbed. When absorption of light takes place, the object no longer emits that color. That particular wavelength is gone forever. If all the wavelengths are absorbed, the object becomes opaque. Glass is not opaque and light does not absorb itself.

The prism is acting as a wavelength selector. The only time that you can see the complimentary colors is when one is blocked, which of course, creates two light sources.

However, cyan, magenta and yellow can be seen with the single slit experiment, also. According to Huygens principle, every point on a wave front acts as a source of spherical wavelets. As the plane waves propagate through the slit, the points on each new wave front creates its own spherical wavelets and each wave front acts as a new light source. The superposition principle that shows when two waves meet in the same phase, a new wave is created that has the amplitude equal to the sum of the amplitude of the two waves, and waves that are out of phase by 180 degrees will become flat, i.e. no light.

So, technically, there should be, not only an additive theory of color, but a subtractive one, as well. One that doesn’t involve any type of absorption. The subtractive model of light itself should integrate two or more light sources along with destructive interference.

Am I wrong? If not, we could call it...the SS theory . Cool

The subtractive selection theory.

What do you guys think?
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#9
(Dec 3, 2019 05:48 PM)Secular Sanity Wrote:
(Nov 28, 2019 03:54 PM)C C Wrote: I still don't get what the issue even is in the thread when the latter shifts from CMY or CMYK subtractive model to prism effects, and items like what "absorb" was referring to in the OP if not the subtraction taking place by the chemicals in the inks, pigments. So clearly I just need to exit altogether since what problem the topic is specifically revolving around eludes me (I'm surely contributing obfuscation as a result of that).

By George, I think I’ve got it.

I'm just going to quickly explain, mostly as a note to self, in order to take advantage of Styrder’s (the keeper of good ideas) hospitality. Big Grin


https://www.youtube.com/watch?v=BVWYL9YVFFE

As it stands, the definition of the RGB additive model is mixing light, with all three, yielding white. The definition of the CMY subtractive model is color created by subtracting (absorbing) parts of the spectrum by the means of matter, such as pigments, dyes, ink, filters, etc. Absorption of all light (all colors) yields black.

I could be wrong but I don’t believe that there is a theory that explains how light interacts with itself to create a subtractive color model.

If you were to take any of the complimentary colors (CMY) and combined them, each color would still contain two components of the RBG spectrum. None of them would be absorbed. When absorption of light takes place, the object no longer emits that color. That particular wavelength is gone forever. If all the wavelengths are absorbed, the object becomes opaque. Glass is not opaque and light does not absorb itself.

The prism is acting as a wavelength selector. The only time that you can see the complimentary colors is when one is blocked, which of course, creates two light sources.

However, cyan, magenta and yellow can be seen with the single slit experiment, also. According to Huygens principle, every point on a wave front acts as a source of spherical wavelets. As the plane waves propagate through the slit, the points on each new wave front creates its own spherical wavelets and each wave front acts as a new light source. The superposition principle that shows when two waves meet in the same phase, a new wave is created that has the amplitude equal to the sum of the amplitude of the two waves, and waves that are out of phase by 180 degrees will become flat, i.e. no light.

So, technically, there should be, not only an additive theory of color, but a subtractive one, as well. One that doesn’t involve any type of absorption. The subtractive model of light itself should integrate two or more light sources along with destructive interference.

Am I wrong? If not, we could call it...the SS theory . Cool

The subtractive selection theory.

What do you guys think?


I simply can't figure out how to put this in an order that will make sense right out of the gate, SS, so you'll probably have to jump back up here again later (after looking at those color production categories further down) to hopefully then decipher why I'm portraying or interpreting the situation this way.

So this is like an emission counterpart to the RGB version that is subtractive rather than additive? Doing it without chemicals absorbing/reflecting? But it's actually in the interference category (and/or dispersion?), not the emission one?

I guess the hump I need to get over is to view an example of actual manipulative color-mixing in the interference category that is the equal (or less) of "additive by emission" (RGB) and "subtractive by reflection" (CMY). Or more than just rainbow colors being produced and their enhancement: https://www.olympus-lifescience.com/en/m...erference/

But suggestion-wise, instead of "subtractive", you might call it "color cancellation" for the destructive interference and "color collaboration" for the constructive interference -- or distinction making somewhere along that line.

Which is to say, I'd make it clear via whatever chosen label for it that this is about "color" in a different context (wave interference). So to avoid that disorienting conflation with what color subtraction (mixing, theory, model, etc) normally refers to. The guy in that video isn't helping trim confusion by titling the spectral blocking he's doing "color subtraction".

But if such was possible (color-mixing derived from wave interference), it would arguably seem to be classified under just that: Interference, not the other two (emission, reflection).

I would like to have started out by asking ourselves: Could color production via emission even permit a "subtractive mixing" counterpart as a member or possibility? (I.e., does the latter entail itself being additive?) But this lengthy bit has to follow to express what's meant.

Interference (and/or dispersion) seems to be a separate category than the emission category that additive color mixing (RGB) either is or is a member of.

Interference (and/or dispersion) seems to be a separate category than the reflective category that subtractive color mixing (CMY) either is or is a member of.

Color Production Methods supplied by: https://physics.info/color/

emission
continuous spectra: hot stuff
the sun, fire, incandescent light bulbs
incandescence
discrete spectra: excited electrons
lasers, phosphors, fluorescent tubes, LEDs, neon tubes, sodium & mercury vapor lamps
luminescence, fluorescence, phosphorescence (reemission)

reflection
opaque bodies
paints, inks, dyes, pigments
hemoglobin
chlorophyll a is bright blue-green and is twice as common as the olive colored chlorophyll b; carotenoids are yellow orange (carrots, squash, tomatoes) two kinds of carotenes have nutritional significance; anthocyanins provide the red purple blue color of red grapes, red cabbage, apples, radishes, eggplants; anthoxanthins pale yellow of potatoes, onions, cauliflower;

transmission
transparent bodies
stained glass, photographic filters, tinted sunglasses, red sunsets

scattering
small suspended particles
nitrogen molecules make the sky blue
foam, froth, clouds, smoke
a colloid is a mixture of small particles of one substance suspendend in another substance: clouds, smoke, haze
emulsions are suspensions of one liquid in another: mayonnaise, cosmetic creams
milk (fat globules 1–5 μm diameter reduced to <1 μm after homogenization, micelles of milk protein casein 0.1 μm diameter)
gels are liquids dispersed in a solid: pudding is water dispersed in starch
sols are solids particles dispersed in a liquid: flour and cornstarch thickened sauces

dispersion
variations in transmission speed
rainbows, diamonds, flint glass, chromatic aberration

interference
path length differences
thin films, insect wings & shells, pigeon necks, peacock feathers, mother of pearl, heat stains on metals, spider webs, halos, bubbles, watered silks, mist on glass, photoelastic stress,
iridescence, opalescence, pearlescence
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#10
(Dec 4, 2019 04:11 AM)C C Wrote: So this is like an emission counterpart to the RGB version that is subtractive rather than additive? Doing it without chemicals absorbing/reflecting? But it's actually in the interference category (and/or dispersion?), not the emission one?

Yes. Exactly! 

Damn, C C, I’ve never been disappointed with your skills, never—not once! You are by far the best dancer (listener) that I’ve ever met.

C C Wrote:I guess the hump I need to get over is to view an example of actual manipulative color-mixing in the interference category that is the equal (or less) of "additive by emission" (RGB) and "subtractive by reflection" (CMY). Or more than just rainbow colors being produced and their enhancement: https://www.olympus-lifescience.com/en/m...erference/

Yes, from what I gather, the only time that interference is used to explain color is with thin film interference, but this is a byproduct of reflection, not just transmission. Similar to my photo of the candles but closer together than the double window panes.

As far as I know, no one has used this explanation to explain transmitted waves before, only reflected ones. If I’m right (big "if"), this would put the conundrum that Goethe, Pehr Sällström and countless others have encountered to rest once and for all. 

C C Wrote:But suggestion-wise, instead of "subtractive", you might call it "color cancellation" for the destructive interference and "color collaboration" for the constructive interference -- or distinction making somewhere along that line.

Damn it! You're right. Okay, if I'm correct then so be it. The new C C color theory. Sounds good to me. Big Grin

I know it's a boring topic but hey, sometimes...the devil is in the details. Wink

I'm heading out of town in a few days. I'll be gone for a week or so. If you don't mind, I would like to tell you more about it when I return.

Thanks again for listening, C C. Thumbs up!
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