Why there is no frequency for the color brown?

[DaTario]

Hi All,

Is it true that the brown color has not a single frequency attached to it?DaTario

 

[Dale]

The same is true of white, or gray, or purple.

 

[Drakkith]

The only colors which have a corresponding frequency(or rather a small, continuous range of frequencies) are spectral colors.

 

[sophiecentaur]

The only colors which have a corresponding frequency(or rather a small, continuous range of frequencies) are spectral colors.

Doesn't it just make you cross that even 'reputable' Science sources confuse wavelength and colour?

 

[Drakkith]

Doesn't it just make you cross that even 'reputable' Science sources confuse wavelength and colour?

Indeed. It makes me 655 nm in the face.

 

[DaTario]

Indeed. It makes me 655 nm in the face.

Is it correct to say that there are colors which are not expressible in terms of a thin an monomodal spectrum?

 

[Dale]

Is it correct to say that there are colors which are not expressible in terms of a thin an monomodal spectrum?

Yes, see my previous reply for a few examples of such non spectral colors.

 

[DaTario]

I saw it. Thank you for sharing, Dale. So it seems that the concept of color has something of the physiology of eye inside, isn´t it?
I have heard of metamerism, i.e., visible radiations with different spectra but recognized by the eye as having equal color. Does it imply that the color concept does not have even an objective association with spectrum?

 

[pixel]

I saw it. Thank you for sharing, Dale. So it seems that the concept of color has something of the physiology of eye inside, isn´t it?
I have heard of metamerism, i.e., visible radiations with different spectra but recognized by the eye as having equal color. Does it imply that the color concept does not have even an objective association with spectrum?

The measurement of color makes use of the reflectance of the object (spectrum), the light source and the three color response curves (color matching functions) for human vision.

 

[Drakkith]

I saw it. Thank you for sharing, Dale. So it seems that the concept of color has something of the physiology of eye inside, isn´t it?
I have heard of metamerism, i.e., visible radiations with different spectra but recognized by the eye as having equal color. Does it imply that the color concept does not have even an objective association with spectrum?

The perception of color is extremely complicated and involves both the eye and the brain. It is also very much subjective. For example, my stepfather is red-green colorblind. To him, a green streetlight at an intersection looks almost exactly like the white streetlights that light up parking lots and such. The green streetlight is just a bit dimmer than the white lights. So for him the spectral color green looks very much like a non-spectral color. He also has difficulty seeing the color yellow. The standard wavelengths given for each spectral color don't apply to him at all.

In addition, even for color-normal people, the brain actively works to make sure that your perception of color changes as little as possible between various environmental light sources. Your perception of the color of your shirt is probably very similar no matter if you're sitting under white fluorescent lights in an office or under a yellowish incandescent at home.

 

[Khashishi]

There are tetrachromatic women who see more colors than most of us. So if you are not so lucky, you see many things as the same color, which they see as different colors.

 

[sophiecentaur]

I saw it. Thank you for sharing, Dale. So it seems that the concept of color has something of the physiology of eye inside, isn´t it?
I have heard of metamerism, i.e., visible radiations with different spectra but recognized by the eye as having equal color. Does it imply that the color concept does not have even an objective association with spectrum?

It's always worth while referring to the https://www.siggraph.org/education/materials/HyperGraph/color/colorcie.htm when discussing colorimetry. It's really worth reading around all the sites that a Google search will throw up. Visible colours (the only colours that exist because colours are in your head) The chart is a totally artificial representation of our (average) perception of colours and mixes of colours and I'm sure there are purists who will cast doubt on such a simplistic representation but the whole mechanism is pretty fuzzy and the accepted human colour analysis curves are only based on 'average' performance.
I'm not sure what you are suggesting here, exactly but it is not actually possible to produce a metemeric match of a spectral colour (i.e. a narrow band of frequencies) by using any combination of primaries because the locus of the spectral colours on the CIE chart is a curve and any straight line joining two primaries will not pass through the required spectral colour. (on the actual curve) You can produce a 'good' yellow (association?) with equal values of R and G signals applied to TV tube primaries but it does not lie on the CIE curve. It will be a 'desaturated' version of spectral yellow and an observer will be able to tell the difference.
There is a difference between how you do colorimetric research and how you make a TV system. The 'best' primaries to use would be monochromatic and spectral but you would never get enough brightness from a narrow band synthesised primary so the ones used are on the vertices of triangles and the spectra of those primaries are far from monochromatic. The gamut of obtainable metameric matches is limited to those colours within the triangle. Note the number of bright clothing colours at sporting events that appear to be the same on the screen. That (imo) must be because they are very saturated and lie outside the obtainable gamut and turn up on the sides of that triangle. If you were at the venue, you would distinguish between all those different bright red kagouls.

 

[LaplacianHarmonic]

You are not studying the correct category. You have to look into the wavelength.

It's a simple matter of looking it up.

 

[sophiecentaur]

You are not studying the correct category. You have to look into the wavelength.

To whom is your remark made?

 

[rumborak]

Color perception is very complex indeed. Just look at that picture that was going around with the yellow (or blue?) dress. The wavelengths and strengths were exactly the same, but to some it looked yellow, to some it looked blue (mostly dependent on where they were looking at the picture).

 

[sophiecentaur]

Color perception is very complex indeed. Just look at that picture that was going around with the yellow (or blue?) dress. The wavelengths and strengths were exactly the same, but to some it looked yellow, to some it looked blue (mostly dependent on where they were looking at the picture).

The Land Retinex theory of colour vision attempts to quantify how we actually perceive colour. See this link and then Google the terms: Land, Retinex Mondrian. It is fascinating and it amazes me that, in the light of his work, colour TV works so well!

 

[pixel]

Color perception is very complex indeed. Just look at that picture that was going around with the yellow (or blue?) dress. The wavelengths and strengths were exactly the same, but to some it looked yellow, to some it looked blue (mostly dependent on where they were looking at the picture).

I think that was just a matter of whether someone's browser was properly color managed and their monitor calibrated (so as you say, where they were looking at it). It didn't really have to do with color perception per se.

 

[Drakkith]

I think that was just a matter of whether someone's browser was properly color managed and their monitor calibrated (so as you say, where they were looking at it). It didn't really have to do with color perception per se.

Sure it did. People would get into arguments over the color after looking at the picture on the same monitor.

 

[pixel]

Sure it did. People would get into arguments over the color after looking at the picture on the same monitor.

That's news to me. There are variations of vision from person to person, but would people looking at the same monitor disagree about whether the dress were yellow or blue, in such large numbers as to become an internet sensation?

 

[nasu]

Yes, they did. I have seen this at work. The same picture on the same phone. Every body, including visitors, was asked about what he/she sees. Definitely two groups, the white-gold group maybe slightly more numerous.

 

[sophiecentaur]

That's news to me. There are variations of vision from person to person, but would people looking at the same monitor disagree about whether the dress were yellow or blue, in such large numbers as to become an internet sensation?

I think people should read about Land's work in detail before questioning his ideas too much. What he found out was not an "internet sensation'. The work was done decades ago.
Colour TV works because it only deals with a limited range of conditions and the sort of 'illusions' that Land came up with are not noticed in everyday life. TV technology is only interested in 'colour fidelity' and presents a limited range of scenes. What our brains happen to make of a number of scenes that are not commonly encountered is a different matter. The relatively simple tristimulus colour vision system is not a complete model. It has nothing to say about what colours will look like in the presence of other nearby coloured areas - it just gives the same RGB values under all conditions (hopefully). A simple way of putting Land's theory is that the eye 'integrates to grey'. We try to eliminate the effects of the illuminant (colour camera white balance settings etc.) and we also try to reduce the colours any scene to something familiar.

 

[DaTario]

TV technology is only interested in 'colour fidelity' and presents a limited range of scenes.

What do you mean by "a limited range of scenes"?

 

[sophiecentaur]

What do you mean by "a limited range of scenes"?

Firstly, additive colour mixing can only represent colours that lie within the triangle with the phosphors at the vertices. That takes care of enough scenes to satisfy most viewers that the coloured regions of the scene are being portrayed 'well enough'. Secondly, the system will just pass on the sort of illusions that Land was producing in his experiments. An isolated patch of colour in a scene will be reproduced the same, whatever colours happen to surround it. It can't compensate for how the brain will experience it.

 

[Drakkith]

Firstly, additive colour mixing can only represent colours that lie within the triangle with the phosphors at the vertices. That takes care of enough scenes to satisfy most viewers that the coloured regions of the scene are being portrayed 'well enough'.

Indeed. This may shock some, but you absolutely cannot render the color violet on a screen. Purple, yes. But not violet. The two are, in fact, different colors.

 

[sophiecentaur]

Indeed. This may shock some, but you absolutely cannot render the color violet on a screen. Purple, yes. But not violet. The two are, in fact, different colors.

Our brain will 'match' spectral violet (outside the triangle) with a colour on the screen that's produced with a lot of B and a smidgen of R and G (inside the triangle).
But that really isn't a problem in most instances because we just don't come across spectral violet (or any other of the colours that are outside the triangle of primaries) in everyday life. The exceptions are when we look at some laser light and very bright saturated colours which are used for clothing and we are just not fussy about the resulting distortion of the colours in a scene. Colour TV has managed to present us with a very good 'near enough' solution. Take your hats off to the early pioneers of colour TV for squeezing all that information into the bandwidth of a conventional TV signal. (And all with analogue processing, too!)

 

[Eric Bretschneider]

Brown is a relative color. It is a lower intensity amber or orange. It can only be perceived in the context of imagery that includes fields of higher intensity colors.

Gray is similar, in that it can only be perceived relative to higher intensity colors/fields. So while a gray image might have the same relative spectral power distribution as the white paper it is printed on, the radiant flux from the gray regions will be lower than the radiant flux from the white paper.

 

[Eric Bretschneider]

Indeed. This may shock some, but you absolutely cannot render the color violet on a screen. Purple, yes. But not violet. The two are, in fact, different colors.

You can in fact render violet, but not at 100% saturation. Then again it is virtually impossible to render any color at 100% saturation on a display. Doing so would require true monochromatic primaries and then you would only render the three primaries at 100% saturation.

The curved outer boundary of a chromaticity diagram represents the limit of 100% saturated colors. The diagonal line on the lower left boundary is the locus of complimentary colors. They are 100% saturated, but require mixtures of violet and red light.

Brown is a special case of amber/orange. It can in fact be 100% saturated, but to "see" brown it has to be in the context of an image with areas of higher luminosity.

 

[Buzz Bloom]

Yes, they did. I have seen this at work.

Yes. I saw demonstrations of this by Land I think in the 1960s. It was quite amazing. One display was of an American flag. The actual colors used to make the display were two different spectral yellows. About half the audience saw approximately normal (not as intense) red, white, and blue colors, and half saw odd colors. What each person saw was stable for them. No one saw yellow.

 

[sophiecentaur]

They are 100% saturated, but require mixtures of violet and red light.

The sources would have to be spectral, too. You couldn't;t get away with the normal trick of fairly broad band phosphors as in TV.

 

[Lish Lash]

Brown does in fact have a central wavelength. It is a dark, desaturated shade of orange, around 620 nm.

 

[John Green]

A fair amount of research since the 1960s suggests that language affects how we perceive colors. For example some languages do not have different words for blue and green and native speakers of those languages do not make much distinction between them and seem to perceive as much more similar than say English speakers.

 

[sophiecentaur]

Brown does in fact have a central wavelength. It is a dark, desaturated shade of orange, around 620 nm.

That is true for some browns but pretty much all real colors are desaturated and many are low luminance. I still think it's unwise to connect wavelength with colour. It's comparing a one dimensional quantity with a (at least) three dimensional quantity.

 

[Drakkith]

You can in fact render violet, but not at 100% saturation.

I assume you mean that the blue pixels on a display have a wide enough spectrum that it includes some amount of violet?

A fair amount of research since the 1960s suggests that language affects how we perceive colors. For example some languages do not have different words for blue and green and native speakers of those languages do not make much distinction between them and seem to perceive as much more similar than say English speakers.

Do you have a good reference or two? This is difficult to believe and I'd like to read more about it.

 

[John Green]

I have not read any Primary sources but here is kind of an overview that does list some sources.
https://en.wikipedia.org/wiki/Blue–green_distinction_in_language
Note that this theory is not without it's detractors.
https://en.wikipedia.org/wiki/Linguistic_relativity_and_the_color_naming_debate

Some popular references.
http://www.apa.org/monitor/feb05/hues.aspx


I am not sure of the veracity of any of this. Just something I ran across while taking a short linguistics class back in the 70s,

 

[Graeme M]

Drakkith, this is what I referred to in my other post. The reference I read claimed that people cannot "see" colors for which they have no words. I assume that means that mechanically their eyes detect these colors and pass them on to the processing of color, but that actual conscious perception (which I think really means discrimination) depends on having a word (or perhaps concept is a better term) for that color. So while mechanically the colors must be available to them, they do not necessarily discriminate in everyday conscious perception. The Berinmo tribe in Papua New Guinea are apparently an example of the blue/green discrimination mentioned above. I suppose this is no different to learning to discriminate between the various flavours in wines - all wine tastes much the same to me because I don't care for it, but connoisseurs can detect far more flavours than I can. Their conscious experience must differ even though mechanically the same processes occur at the level of detection.

 

[sophiecentaur]

The reference I read claimed that people cannot "see" colors for which they have no words.

I really doubt that people would not find two different metemeric matches when presented with a sample image and being told to adjust the RGB controls on a TV display (no mention of naming the colours). I am very suspicious of psychological tests that are aimed at 'proving' a theory for such a complex process. Sounds very much like the way politicians behave.

 

[Graeme M]

sophiecentaur I wondered at this too. I think it very likely that they can discriminate when the question is posed in a mechanical manner, but not so much when posed as a psychological matter. Perhaps in such cases, people simply don't bother to discriminate even though capable of it. Nonetheless, it seems a well studied subject.

http://journals.sagepub.com/doi/abs/10.1177/1069397104267890

And this research may be especially relevant:

http://www.sciencedirect.com/science/article/pii/S0960982207014819

 

[John Green]

Sounds very much like the way politicians behave.
Can't say I disagree with that.

 

[sophiecentaur]

There is parallel here with Music vs Sound. Recognising musical chord progressions is something that needs to be learned (except if you're a musical genius). You hear a song and you perhaps recognise that a melody is involved but someone who 'knows' about music will know how the song works. The proverbial 'tone deaf' listener can still be aware that changes are happening to the sound but cannot analyse it.

 

[DaTario]

I would like to kindly ask someone in this debate to clearify the following concepts, which seem to be associated to this discussion:
1) saturation
2) metemeric
3) hue

Best wishes,

 

[sophiecentaur]

Have you searched those terms? What have you found out for yourself?

 

[DaTario]

Have you searched those terms? What have you found out for yourself?

The first two have been used in this thread. The last one is a word that a friend of mine frequently uses in discussions about the physics of light.

 

[SlowThinker]

(about green-blue indifference)

Do you have a good reference or two? This is difficult to believe and I'd like to read more about it.

Some time ago I experienced something similar. I had to remember a color, then walk for a few seconds, and compare that old color to another one. I realized that I can't really remember a color, only its name, and if I didn't have a good name for it, I had to return several times for the comparison and still wasn't sure.
This might be only limited to simple colors though.
Using sound as an analogy, I can't tell 1kHz sine wave from 1.1kHz but I can easily tell when I hear a remake of a song I heard 20 years ago.
Going back to colors, perhaps I could tell one light-green from another if there was a patch of yellow lying around.

 

[sophiecentaur]

What have you found out for yourself?

The first two have been used in this thread.

And what have you found out for yourself? PF is not just a lazy man's source of the meanings of words. It's for discussing topics, based on some input from the participants.

 

[DaTario]

Sophiecentaur, I respectfully believe PF is a source of the meaning of words and concepts. Those who know their meaning try to help the ones who don´t know, but want to know. If you are calling me lazy I suppose you have some evidence to support this inference. Nowadays, it is becoming difficult to ask a friend what is the name of the band who played with Sting in Bring on the Night, because it seems you are lazy for not having asked Google first. I confess I prefer to ask you than google. If you don´t want to answer, it is up to you. I respect. But you should not generalize, thinking everyone here doesn´t want to get involved in a talk with some other person who hasn´t asked "google". It seems to me that some good conversations sometimes begins with lazy talks (but at the same time interested talks). I love physics and I get worried seeing people like you using hard words with others as if it was a symbol of your knowledge, seriousness or intelectual content. I hope you find your own happy place in this forum.

Answering your question, I have not looked up in the internet what hue is, but once, discussing with a colleague physiscts, I heard him saying that it is a useful and preferable concept in dealing with contexts where color plays a significant role. I can´t remember exactly what the subject of our discussion was. But let me emphasize that my ignorance doesn´t make me fragile in front of your intention to appear a serious scientist. Finally I would dare to place here a piece of advice: if you don´t want to answer a question here, a sound option is to remain silent. Let those who want to collaborate do it.

I really don´t know how much power is given to the author of the OP, but anyway I would like to formally ask this thread to be closed due to the occurence of personal ofence.

 

[DaTario]

Sorry. It would be contradictory for me to assume LAZY is an ofence. I don´t think so. If you have called me lazy, I think I must not feel ofended. Sorry, Sophiecentaur.

 

[Drakkith]

Answering your question, I have not looked up in the internet what hue is, but once, discussing with a colleague physiscts, I heard him saying that it is a useful and preferable concept in dealing with contexts where color plays a significant role. I can´t remember exactly what the subject of our discussion was. But let me emphasize that my ignorance doesn´t make me fragile in front of your intention to appear a serious scientist. Finally I would dare to place here a piece of advice: if you don´t want to answer a question here, a sound option is to remain silent. Let those who want to collaborate do it.

The problem is that finding the basic definition or use of most words and concepts is trivially easy and you can usually find a wealth of information with perhaps only slightly more effort, if any at all. These sources are often far better equipped to give you the basic information on a topic than anyone here at PF is and you're essentially offloading the small amount of effort it takes to look up these words on to someone else. It's like having a book in front of you and asking someone else to open the book to the page you want. It's trivial, but generally annoying to those being asked and is usually taken to mean that the person just doesn't care that much.

 

[DaTario]

Ok, Drakkith, but don´t you agree that there are several questions of this kind (in this forum) in which some patient person, instead of complaining, takes the task to inform what was asked (it may be something that could be obtained basically in the internet) and that interaction simply flows naturally?

My point is that sometimes a trivial question may serve as a start to a discussion, and it can also start a relationship between two persons.
By adopting the rule in which if I don´t think this question deserves an answer, I simply don´t give an answer to it, one gives chance to the appearance of good interactions. The use of hard words seems to be far from necessary in cases like this.

 

[DaTario]

Despite the seismic event, I would like to express deep gratitude to all that have contributed to this thread, including, of course Sophiecentaur, who gave perhaps one of the most significant ones.

 

[Drakkith]

Ok, Drakkith, but don´t you agree that there are several questions of this kind (in this forum) in which some patient person, instead of complaining, takes the task to inform what was asked (it may be something that could be obtained basically in the internet) and that interaction simply flows naturally?

My point is that sometimes a trivial question may serve as a start to a discussion, and it can also start a relationship between two persons.

Of course. But I'd be willing to bet that there are far more instances of such relationships developing when the person asking the question has done some basic legwork first.

By adopting the rule in which if I don´t think this question deserves an answer, I simply don´t give an answer to it, one gives chance to the appearance of good interactions. The use of hard words seems to be far from necessary in cases like this.

If you don't think someone's question deserves an answer, and you don't tell them, how will they learn to write better questions?