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Is “imperfect black”, (anything other than a black hole or vacuum), actually a color?

Nothing absorbs all light except for a black whole, or a vacuum which doesn’t reflect light. If we consider black to be “the absence of light”, nothing is really black.

So things humans perceive as black, a black bear’s pelt, a black shirt, a black car, etc, what color are these?

If you shine a bright enough white light at a “black” object, it’s eventually going to appear white. Depends on the reflectivity of the black object. Vanta black vs a black plastic cup. However vanta black still reflects some light.

So what color are these “black” objects? Are they white, as they would seemingly appear when a bright white light is shown on them, or are they maybe, an extremely dark orange, or an extremely dark blue, or an extremely dark yellow, which, when exposed to enough white light, could be perceived as such.

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Or maybe I’m getting it all wrong. Because a red object doesn’t truly absorb all light except “red” (approx 620 to 750 nm), it reflects some other wavelengths too according to this graph: enter image description here

And according to this graph which I just found, black anbsorbs everything, (but that’s of course “perfect black”, or a black hole).:enter image description here

So I guess what I’m truly asking is, do “imperfect black” objects peak reflectivity in specific ranges of wavelengths, ie. Are they a specific color, or simply very dark white. And maybe it depends on which chemical/dye is being used to produce “black”.

P.S. bonus question. That “red object” in figure one, what is that supposed to represent? Surely there’s no such thing as a “red object” or “green object”, it totally depends on what dye is being used. What type of “model”, (red object), were said “spectral reflectance curves” calculated with? Related: Could you make something that reflected a much smaller light curve, ie. just maybe 3nm of range?

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If we consider black to be “the absence of light”, nothing is really black.

While true, things can be black enough that our visual system doesn't register any light from it. In that case it looks the same as something that is truly reflecting nothing.

It also depends on the environment. Vanta black is easily seen at high angles in full sunlight. Meanwhile much better reflectors may appear completely black in a dark room.

So what color are these “black” objects?

Are you asking what the color is (which is a perceptual question by a person looking at it), or are you asking about a description of the reflected spectrum?

All that is required for it to appear black to us is that is has very low levels of light coming from it. The minimal light that it does show is unconstrained. The spectrum might be similar to the environment, just reduced in total. Or one portion of the spectrum might be much stronger than others. As long as the reflectivity is low enough, all will look black.

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  • $\begingroup$ “A description of the reflected spectrum.” So basically you’re saying that yes, any object that appears black to us really is most likely—according to its reflected spectrum—a very dark blue, red, yellow, orange etc? Or maybe even white. | In regards to it looking similar to its environment, in this scenario consider it to be in a vacuum with white light shining on it. $\endgroup$
    – Name here
    Commented Aug 3, 2023 at 8:54
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    $\begingroup$ Color isn't spectrum. It's a mental construct. Two objects with identical spectra may have different colors in different situations. (Remember the dress?). Environment may include states of the observer as well as the object. So I would never be comfortable agreeing with "it appears to be color X, but it really has color Y". I could agree with "It has a spectrum that is similar to objects that normally appear Y" $\endgroup$
    – BowlOfRed
    Commented Aug 3, 2023 at 9:35
  • $\begingroup$ Well no matter what, you can measure what wavelength of radiation is coming from it, and what wavelengths it peaks in. It literally is a spectrum. As with the dress, again you could measure the spectra reflecting off of it and and see its literal emissions. What you’re referring to is human perception. $\endgroup$
    – Name here
    Commented Aug 4, 2023 at 10:00
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Are they a specific color, or simply very dark white?

Any sufficiently dark object will appear black to us, especially if contrasted against a much lighter background of nearby objects.

To use RGB notation, a dark red [1,0,0], dark green [0,1,0], or dark blue [0,0,1] will all appear 'black' in an image with any reasonable lighter spots, unless we contrast them with [0,0,0] or each other.

There's no need for the 'very small amount of light' reflected to be white, it could just as well be any colour.

As an almost unrelated anecdote, my father always used to add a little bit of blue paint to any black he was using, as he said it made it 'more black'. This is more about the mix of pigments required to get a good absorption across the spectrum, and personal preference, than actually measuring the relfectence of any coating, or trying to define the phrase 'imperfect black'.

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