Why is "silver" percieved as "grey" in colour?


by Molydood
Tags: colour, grey, percieved, silver
Molydood
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#1
Oct28-09, 05:39 AM
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I think we can probably agree that grey would be the closest approximation to the colour of reflective surfaces.
I am guessing this is similar to the way in which auto exposure works on cameras in that they assume that the entire scene will be 18% grey overall (because the 'average' tone ends up thereabouts for most pictures if you consider every pixel)

I am thinking diffuse silver more than anything, but even super shiny things like mirrors and metallic objects fall into this category of looking a bit "grey" and I can only think it is for the same reason in that our eyes donít focus on the individual elements relecting off a mirror, but instead average the tone of the object to about 18% grey. If you focus on individual reflections it may look less grey, but if you glance at a shiny object, I reckon grey would be my brains first thoughts, and that is the only reason I can think why.

Is this true?
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jmatejka
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#2
Oct28-09, 06:00 AM
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Human cone limited sensitivity plays a big part in our perception of color, or sometimes "mistaken" perception.

In a previous post, of a similar nature, this question was asked.........

"However, the way how mixture of blue and red looks violet doesn't make sense equally, because the violet is not in between blue and red in the spectrum."

Here is a link to that post, some good human visual physiology information is there, the links at the top are very informative:

http://www.physicsforums.com/showthr...ghlight=Violet

Hopefully this helps some with the human perception of color.
Molydood
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#3
Oct28-09, 07:22 AM
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interesting but not sure it answers the question.
unless I missed something of course...

mikeph
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#4
Oct28-09, 07:55 AM
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Why is "silver" percieved as "grey" in colour?


My guess would be because grey is a dimmer version of white, which is the most intensely perceived colour that we see in everyday life, representing the imperfect reflectivity of most metals. Although in some cases the reflected light is very bright and close to white.
Danger
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#5
Oct31-09, 04:21 AM
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I might be missing something here, but in my experience a reflective surface such as a mirror has no colour; it merely redirects the colour of whatever you see the reflection of.
In an art programme, though, grey is necessary in that a monitor or printer can't properly reproduce the reflective surface. That drove me nuts when I first started using Illustrator, but you get used to it after a while.
Molydood
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#6
Oct31-09, 10:01 AM
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Quote Quote by Danger View Post
I might be missing something here, but in my experience a reflective surface such as a mirror has no colour; it merely redirects the colour of whatever you see the reflection of.
In an art programme, though, grey is necessary in that a monitor or printer can't properly reproduce the reflective surface. That drove me nuts when I first started using Illustrator, but you get used to it after a while.
Indeed it does but as I said I was thinking primarily of diffuse silver surfaces. I did go on to mention that a 'glance' at a silver (specular) object could also appear as 18% but maybe your peception is different. I believe it is the same effect in both cases: an averaging of tones.
DaveC426913
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#7
Oct31-09, 10:12 AM
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1] If you take some silver that is not polished to high reflectivity, I do believe that the metal itself is actually whiteish-grey.

2] Grey is the average hue (colour) and the average value (black-white). Unless there is something in the scene that dominates in terms of hue or dominates in terms of value, the scene will simply average to somewhere in the middle.


Note that "grey" is an extremely broad target to hit value-wise. (In fact, it requires some pretty contrived circumstances to miss the target.)

If it's not actually white, and not actually black (both of which are extremes and practically impossible to achieve in the real world), then you've pretty much got grey. But that doesn't mean that all scenes are the same grey.

And note that the same thing occurs hue-wise. You've got warm-greys and cool greys. We just call em grey.
Andy Resnick
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#8
Oct31-09, 10:59 AM
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As others have pointed out, it's not the neutral color of silver that is interesting, as most metals have that color. What is more interesting is why gold and copper have non-neutral reflectivities- it's due to relativistic effects:

http://math.ucr.edu/home/baez/physic...old_color.html
DaveC426913
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Oct31-09, 11:52 AM
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Quote Quote by Andy Resnick View Post
As others have pointed out, it's not the neutral color of silver that is interesting, as most metals have that color. What is more interesting is why gold and copper have non-neutral reflectivities- it's due to relativistic effects:

http://math.ucr.edu/home/baez/physic...old_color.html
A disappointingly vague article. What relativistic effects?
Bob S
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#10
Oct31-09, 12:31 PM
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Silver metal does not polish to a mirror surface, but if it is deposited onto a glass surface, it does have a mirror surface, but it oxidizes quickly unless protected.
Bob S
Andy Resnick
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Oct31-09, 01:21 PM
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Quote Quote by DaveC426913 View Post
A disappointingly vague article. What relativistic effects?
Oh, the pleasure of finding things out for oneself.

http://www.ncbi.nlm.nih.gov/pubmed/15945680
http://www.sciencedirect.com/science...11064892798baf
sophiecentaur
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#12
Oct31-09, 01:22 PM
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Quote Quote by Bob S View Post
Silver metal does not polish to a mirror surface, but if it is deposited onto a glass surface, it does have a mirror surface, but it oxidizes quickly unless protected.
Bob S
If you're talking about high purity Silver, it doesn't oxidise that fast. Standard ('stirling') silver has something like 7% of copper in the alloy and that tarnishes very quickly.

And, with care and jeweler's rouge, you can get a pretty damn good mirror surface- particularly with Britannia Silver (look at the inside of a new silver tablespoon). The problem is that it (Britannia) is very soft and will scratch very easily and it wouldn't be much better than Lead for cutlery..

I was interested in the idea that the inner electrons contribute so much to the reflectivity. I always thought that it was the conductance electrons that were responsible in metals. That is true for Radio Frequency reflection, I think. Or, perhaps the colouration is very slight and the reflection effect is still dominated by the conductivity effect.
Redbelly98
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#13
Nov1-09, 12:59 PM
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This one came closest to answering the question in the abstract. To summarize:

Gold's energy levels allow for stronger absorption of green wavelengths and shorter, giving rise to its yellow appearance.

If you ignore relativity, you'll get the wrong values when you calculate atomic orbitals. The (mis)calculated orbitals allow for stronger absorption at u.v. and shorter wavelengths, with a nearly uniform (i.e. gray) reflectivity for visible wavelengths.
DaveC426913
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#14
Nov1-09, 05:32 PM
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Quote Quote by Andy Resnick View Post

Well what's the point in a linking to something to shed some light if it doesn't shed some light?


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