Is Black a Colour? Examining the Definition and Perception of Black as a Colour

[Farsight]

I reckon black is an absence of colour, so it's not really a colour. But it is on my colour chart, and I am wearing black jeans. So if somebody wants to say black is a colour fair enough. Or color. I'm easy.
The thing is, none of these "colours" really exist anyhow. I mean, I might ask "Is red is a colour?", and everybody would say yes. But colour is just something in our heads, the brain's shorthand "colour coding" for frequency. Colour doesn't really exist. It really doesn't. We only think it exists.

But it doesn't really!

 

[zoobyshoe]

But colour is just something in our heads, the brain's shorthand "colour coding" for frequency. Colour doesn't really exist. It really doesn't. We only think it exists.

But it doesn't really!

The brain sorts out the frequencies, dresses them up, so to speak, and presents them to consciousness as the colors we know and love.

 

[GeoMike]

The brain sorts out the frequencies, dresses them up, so to speak, and presents them to consciousness as the colors we know and love.

Makes your brain hurt trying to imagine what new "colors" infrared and ultraviolet would be if we could "see" them.

-GeoMike-

 

[zoobyshoe]

Makes your brain hurt trying to imagine what new "colors" infrared and ultraviolet would be if we could "see" them.

That would be so cool to have two new colors!

 

[ZapperZ]

I reckon black is an absence of colour, so it's not really a colour. But it is on my colour chart, and I am wearing black jeans. So if somebody wants to say black is a colour fair enough. Or color. I'm easy.
The thing is, none of these "colours" really exist anyhow. I mean, I might ask "Is red is a colour?", and everybody would say yes. But colour is just something in our heads, the brain's shorthand "colour coding" for frequency. Colour doesn't really exist. It really doesn't. We only think it exists.

But it doesn't really!

Then you don't exist either. Would you rather this thread be moved to the philosophy forum where this type of discussion can go on ad nauseum?

Zz.

 

[zoobyshoe]

Then you don't exist either. Would you rather this thread be moved to the philosophy forum where this type of discussion can go on ad nauseum?

Zz.

Actually ZapperZ, his post is factual and not philosophical. Colors as we experience them are created in the brain and are not a property of the EM wavelengths they represent. There is no objective reason that EM wavelengths between 625 and 740 nanometers should look red to us. There's no reason any color should be anything but a shade of grey. Our brains add the spice of colors as we percieve them. This is a neurological fact that you could confirm with Mentor Hypnagogue or selfAdjoint.

 

[redrocks]

hmmmm... in the art world Black is a Shade.

 

[zoobyshoe]

hmmmm... in the art world Black is a Shade.

But so is white, and every level of grey in between.

 

[Gokul43201]

Actually ZapperZ, his post is factual and not philosophical. Colors as we experience them are created in the brain and are not a property of the EM wavelengths they represent. There is no objective reason that EM wavelengths between 625 and 740 nanometers should look red to us. There's no reason any color should be anything but a shade of grey. Our brains add the spice of colors as we percieve them. This is a neurological fact that you could confirm with Mentor Hypnagogue or selfAdjoint.

Is the frequency of a radiation any more a real property of the radiation than its "color" is?

The frequency is simply a number that is spit out by a machine (a spectrometer) that is irradiated by the light. The color is, in much the same way, a signal spit out by a different kind of machine (an eye), when exposed to the same light.

This does become a philosophical discussion.

 

[zoobyshoe]

Is the frequency of a radiation any more a real property of the radiation than its "color" is?

The frequency is simply a number that is spit out by a machine (a spectrometer) that is irradiated by the light.

This, I don't understand, so you'll have to explain it. I started a thread once asking what was meant by the term "frequency" when applied to photons, but it didn't seem anyone could put it in terms accessible to someone who hadn't studied quantum physics. I did leave, however, with the distinct impression that photons are authentically doing something at the specific frequencies ascribed to them; changing their quantum phase or some such. No one suggested anything to the effect that the frequencies might be fictional or arbitrarily ascribed.

The color is, in much the same way, a signal spit out by a different kind of machine (an eye), when exposed to the same light.

The eye is a reciever and the signals it gathers are sent to various parts of the brain for processing. At the end it of it all, different ranges of frequencies are presented to consciousness as red, blue, yellow, and so forth. So, the cones gather the frequencies selectively but the "machine" responsible for fictitiously enriching them into the experience of color, is the brain.

We have to suppose this was the same kind of accidental mutation that goes on all the time in evolution. Despite being a "fictional" perception it proved so much more useful in sorting the environment out than just seeing things in many shades of grey, that the first people who saw this way did better than their black and white visioned contemporaries and eventually supplanted them.

 

[ZapperZ]

Actually ZapperZ, his post is factual and not philosophical. Colors as we experience them are created in the brain and are not a property of the EM wavelengths they represent. There is no objective reason that EM wavelengths between 625 and 740 nanometers should look red to us. There's no reason any color should be anything but a shade of grey. Our brains add the spice of colors as we percieve them. This is a neurological fact that you could confirm with Mentor Hypnagogue or selfAdjoint.

It does become "philosophical" when you start to consider if something "exist". "color" is how we perceive certain EM frequency. It isn't quantitatively accurate, but it is certainly not something we imagined. It is no different than having a trigger that goes BAM when an EM radiation of a certain frequency hits it.

If you accept his logic as color not existing, then you should accept also that you don't exist, because all you are is what *I* perceived in my brain. This is what I mean as it being no longer a physics discussion.

Zz.

 

[zoobyshoe]

It does become "philosophical" when you start to consider if something "exist". "color" is how we perceive certain EM frequency. It isn't quantitatively accurate, but it is certainly not something we imagined. It is no different than having a trigger that goes BAM when an EM radiation of a certain frequency hits it.

If you accept his logic as color not existing, then you should accept also that you don't exist, because all you are is what *I* perceived in my brain. This is what I mean as it being no longer a physics discussion.

Zz.

I think I understand your objection to what he said.

When I read it, I disliked the way he said it, but didn't take it to be the grounds of anything like a developed philosophical stance, just a poorly expressed, over exited reaction to an "amazing" piece of information. My mind was boggled when I first found this out as well, so I refrained from pointing out that saying "We only think it exists" is not an articulate way of expressing the phenomenon of our experience of color. I thought he just lacked the sophistication to phrase it in a way that wasn't inadvertantly misleading.

 

[Danger]

We have to suppose this was the same kind of accidental mutation that goes on all the time in evolution. Despite being a "fictional" perception it proved so much more useful in sorting the environment out than just seeing things in many shades of grey, that the first people who saw this way did better than their black and white visioned contemporaries and eventually supplanted them.

I can't remember the details, but a SciAm article a couple of issues back on how birds see provides evidence that early humans (or their forebearers) possessed 4 types of cone cells and degraded to the 3 that we now have.

 

[zoobyshoe]

I can't remember the details, but a SciAm article a couple of issues back on how birds see provides evidence that early humans (or their forebearers) possessed 4 types of cone cells and degraded to the 3 that we now have.

I read that, at least some birds, can see in the ultraviolet range. So it sounds like the article you read is suggesting humans once could as well.

You recall what made them suspect this?

 

[Danger]

Not right off, but I still have the issue at home. I think that it was by tracking eye development through various stages of evolution in general to see where birds and mammals differentiated as to visual structures. I'll look for it when I'm done work.

 

[NoTime]

I can't remember the details, but a SciAm article a couple of issues back on how birds see provides evidence that early humans (or their forebearers) possessed 4 types of cone cells and degraded to the 3 that we now have.

Actualy, some still do, but IIRC its lower into the red not UV.

A small mention of tetrachromats in the following
http://en.wikipedia.org/wiki/Color#Spectral_colors

 

[zoobyshoe]

Actualy, some still do, but IIRC its lower into the red not UV.

A small mention of tetrachromats in the following
http://en.wikipedia.org/wiki/Color#Spectral_colors

But not infra-red, (which would be cool):

Also, evidence suggests that some very few humans are tetrachromats, a phenomenon which presumably arises when an individual receives two slightly different copies of the gene for either the medium- or long-wave cones. It can be supposed that, for genetic reasons, the small numbers of human tetrachromats that do exist are overwhelmingly female. Their color discriminations are only slightly enhanced, but their brains do appear to adapt to use the additional color information.

 

[Chaos' lil bro Order]

Originally Posted by Chaos' lil bro Order
Dave gives the best answer so far. This definition satisfies that an object can be black because any incident light is absorbed by it and that an object can be black because there is no incident light whatsoever. The point is, as Dave succinctly pointed out, is that 'no light is emitted from [the object].'

All other discussion is wrong.

Ouch! Can't disagree more. Is a perfect reflector black?

I'm not sure I understand your objection Gokul. I don't recall saying perfect reflection makes an object black. Can you elaborate please.

 

[Chaos' lil bro Order]

Bees can see the UV rays emitted from flowering plants (read David Bodanis' 'The secret house').

Snakes have pits on their head that detect Infrared (re: hunting for mice at night).

Humans have a so-called 'third eye' technically called the pineal gland located under the forehead. Science does not know much about this gland and many suppose its a vestigial remnant. Interestingly, many birds have this gland much closer to the surface of their forehead (possibly to detect the Earth's magnetic field for migration compassing purposes?)

People always talk about cones as being our 'color detectors', but few people know that cones are actually at the back of the retina. Incident light must first travel through many layers of cells in the Plexiform layer of the retina. These cells include (in order of interaction with incident light) Ganglion cells, Amacrine cells, Bipolar Cells, Horizontal Cells AND THEN cones and rods. Many researchers believe Ganglion cells may also act as photoreceptors in addition to the familiar cones and rods. It is also wise to postulate that both Ganglion cells and cones/rods are photoreceptors and their redundancy is part of a fact-checking error correction system. This postulate gains extra credence by the fact that there are many subsystems in the retina that WE KNOW to be utilizers of a fact-checking error correciton system (re: feedback loops in horizontal cells).

If anyone has a question, please ask it, as this is my area of expertise. Finally I won't have to step on Zapper's QM knowledge or SpaceTIger's Cosmology knowledge!

 

[Gokul43201]

I'm not sure I understand your objection Gokul. I don't recall saying perfect reflection makes an object black. Can you elaborate please.

A perfect reflector has an emissivity of zero (from energy conservation and Kirchoff's Law). So, if it emits no light...

 

[DaveC426913]

A definition was put forth (https://www.physicsforums.com/showpost.php?p=1091947&postcount=19") that "A thing is black if it absorbs all the visible radiation incident upon it". This is a needless condition - whether the object absorbs anything is irrelevant. The only requirement for an object to be black is that no photons are coming from the object. (eg. In a dark room, the object absorbs no photons.)

A perfect reflector has an emissivity of zero (from energy conservation and Kirchoff's Law). So, if it emits no light...

I think you're bifurcating bunnies here. Correct me of I'm wrong but, without worrying about the details, an object reflects photons by absorbing them and re-emitting them. We don't call this emission, but technically it is.

Nonetheless, if "no emissions" is technically unacceptable, then can we come up with a term that means "no photons leave the object"?

 

[Andrew Mason]

A definition was put forth (https://www.physicsforums.com/showpost.php?p=1091947&postcount=19") that "A thing is black if it absorbs all the visible radiation incident upon it". This is a needless condition - whether the object absorbs anything is irrelevant. The only requirement for an object to be black is that no photons are coming from the object. (eg. In a dark room, the object absorbs no photons.)

But in your definition colour is not an attribute of the object but an attribute of the light that falls on it.

AM

 

[Farsight]

Zoobyshoe, I was rather trying to keep things simple. And fun.

Zapper, in my humble opinion, whether colour actually exists is something more than philosophy. What definitely exists is frequency, a cyclic variation. We can measure this. Yes, we can assign a colour, but the colour is not actually out there in the world we are trying to study. It's an internal label for information processing. In similar vein we can model molecules and work out the arrangement of atoms, but the smell of them is not actually there either. Going further we can talk about heat, a "derived effect" of motion. We all know about heat and how it burns, but we tend to start talking about heat flow as if heat is an actual fluid. Or people talk about pure energy as if it's something you can hold in your hand, forgetting that it is the property of a system. My point is that the science becomes coloured, corrupted even, by our perception, and the loose linguistic baggage that we take for granted. Rigour is compromised.

Andrew, perhaps that should be an attribute of the light that comes from it.

 

[ZapperZ]

Zapper, in my humble opinion, whether colour actually exists is something more than philosophy. What definitely exists is frequency, a cyclic variation. We can measure this. Yes, we can assign a colour, but the colour is not actually out there in the world we are trying to study. It's an internal label for information processing. In similar vein we can model molecules and work out the arrangement of atoms, but the smell of them is not actually there either. Going further we can talk about heat, a "derived effect" of motion. We all know about heat and how it burns, but we tend to start talking about heat flow as if heat is an actual fluid. Or people talk about pure energy as if it's something you can hold in your hand, forgetting that it is the property of a system. My point is that the science becomes coloured, corrupted even, by our perception, and the loose linguistic baggage that we take for granted. Rigour is compromised.

It is one thing to say such a description is inaccurate. It is ANOTHER to say it doesn't exist! I would say that you don't exist either.

I would put it to you that assigning a number to the value of frequency is no different than assigning "color". You are still putting a "label" on it. You just don't realize it.

Zz.

 

[Farsight]

Actually Zapper, the existence of my consciousness is a very interesting question. I can't see it, or smell it, or weigh it, or touch it. I can't prove it exists. All I can do is experience it. And it is all that I do experience. It's nothing and everything. It's totally imaginary, yet totally real. It doesn't exist, or does it? Let's not consign this sort of thing to philosophy just because we can't be bothered to think up an experiment. Especially seeing as it rather reminds me of money. And money reminds me of energy.

 

[ZapperZ]

Actually Zapper, the existence of my consciousness is a very interesting question. I can't see it, or smell it, or weigh it, or touch it. I can't prove it exists. All I can do is experience it. And it is all that I do experience. It's nothing and everything. It's totally imaginary, yet totally real. It doesn't exist, or does it? Let's not consign this sort of thing to philosophy just because we can't be bothered to think up an experiment. Especially seeing as it rather reminds me of money. And money reminds me of energy.

If you don't think that what you said here does not belong in physics, then there's nothing else to be said to you.

Zz.

 

[Farsight]

Anyhow, is black a colour?

Yes. It is our internal label for frequency 0.

Edit: Maybe not physics, Zapper. But Brain Science, not philosophy.

 

[NoTime]

But not infra-red, (which would be cool):

I might have the longer wave version of the long-wave cones.
In any event I can see when supposedly IR leds and lasers are opereating.
For example most remote controlers.
Exposed led ones are fairly easy to see. Some of the covered ones are barely (or not) detectable and the room lights needs to be dimed, but I don't have to wait for dark adaption.

I wonder how common this is.

Bigest thing I've noticed is that sometimes people will call red for what I would call a red/orange

 

[Farsight]

That sounds unusual, NoTime. I've heard of people who can see some way into the UltraViolet range, but not the other way. Maybe there's something here:

http://www.4colorvision.com/files/tetrachromat.htm

"Tan reported, and Griswold & Stark confirmed, that the spectral response of aphakic humans extended well into the area of 300-400 nm..."

 

[Farsight]

All: I think this has been posted up before, apologies if it's old news. But it's particularly relevant here because it tells us something important about perception and colour, which we need to appreciate when we're trying to be rational about questions like Is black a colour? It seems rather incredible, but in simple terms you end up with something like this:

Q: When is blue yellow?
A: When they're both grey.

Try it:

http://www.echalk.co.uk/amusements/OpticalIllusions/colourPerception/colourPerception.html

 

[Chaos' lil bro Order]

A perfect reflector has an emissivity of zero (from energy conservation and Kirchoff's Law). So, if it emits no light...

If something emits no light, its a perfect blackbody. A perfect blackbody has an emissivity = 1. A perfect reflector has an emissivity = 0. You are intertwining reflection and emission as the same concept. If something emits no light, its black. Case solved.

 

[Chaos' lil bro Order]

It is one thing to say such a description is inaccurate. It is ANOTHER to say it doesn't exist! I would say that you don't exist either.

I would put it to you that assigning a number to the value of frequency is no different than assigning "color". You are still putting a "label" on it. You just don't realize it.

Zz.

This notion has been beaten to death in the Dr.Chinese 'Realism' post. Everything we know is a semantical construct predicated upon observational experience. No news here. I'm sure FarSight gets this point. Heck, I think we all realized this point in our teenage years, its not really that deep.

I would make one distinction that may sound stupid and overphilosophical, but here it goes anyways... Human assign a number value to frequency, but frequency assigns a color value to our minds.

 

[Farsight]

Guys: I really want to draw your attention to this astonishing colour perception demonstration. Please do follow the link. It's a real gobsmacker, I couldn't believe it when I first saw it. But amazingly, it's true:

http://www.echalk.co.uk/amusements/OpticalIllusions/colourPerception/colourPerception.html

Q: When is blue yellow?
A: When they're both grey.

 

[zoobyshoe]

I might have the longer wave version of the long-wave cones.
In any event I can see when supposedly IR leds and lasers are opereating.
For example most remote controlers.
Exposed led ones are fairly easy to see. Some of the covered ones are barely (or not) detectable and the room lights needs to be dimed, but I don't have to wait for dark adaption.

You might contact someone who studies vision and offer yourself to be tested for this. It shouldn't be too difficult to design set ups to quantify the extent of your ability to do this.

I wonder how common this is.

Bigest thing I've noticed is that sometimes people will call red for what I would call a red/orange

In the case of pigments I only recently became aware that most of what passes for red in the medium of colored pencils is actually red-orange. There is a lot of yellow present that makes mixing purples from these alleged reds impossible. You end up with overly greyed results. The only really successful purples come from magenta and related shades, and not the "reds".

I could see the difference between "reds" and magentas before but now I am alert to the fact that the "reds" are actually richer red-oranges.

 

[DaveC426913]

In the case of pigments I only recently became aware that most of what passes for red in the medium of colored pencils is actually red-orange. There is a lot of yellow present that makes mixing purples from these alleged reds impossible. You end up with overly greyed results. The only really successful purples come from magenta and related shades, and not the "reds".

I could see the difference between "reds" and magentas before but now I am alert to the fact that the "reds" are actually richer red-oranges.

More generally, the reds you're using are "warm" reds (which means they have a lot of yellow). You should adhere to the guideline of mixing warm tones only with warm tones and cool tones only with cool tones. Crimson Lake and Cherry and related tones are cool reds and will mix well with your purples.

In fact, most artists tend to keep a warm and a cool of each colour on their palette.
Canary and lemon yellow are cool while school bus yellow is warm.
Azure is cool while sky blue is warm.
Forest green cool, lime green warm. etc.

 

[NoTime]

You might contact someone who studies vision and offer yourself to be tested for this. It shouldn't be too difficult to design set ups to quantify the extent of your ability to do this.

I was just curious to see if others could see their remotes light up.
Its easier if you turn the room lights off.
And try different ones, they vary quite a bit in brightness.
Or maybe it's just time to change the batteries

FWIW they look red.
The same color red as a visible red led.
It's the relative receptor activation that defines the color you see more than frequency.
All frequencies below the middle wave receptor activation point look red.

 

[zoobyshoe]

More generally, the reds you're using are "warm" reds (which means they have a lot of yellow). You should adhere to the guideline of mixing warm tones only with warm tones and cool tones only with cool tones.

I've only dabbled with paint, at this point anyway, and colored pencil designations are different, which makes crossover by color name problematic. The Prismacolor Crimson Lake was discontinued a long time ago, and they've never made a Cherry red. Everything now designated a "red" would be one of the "warm" reds you mentioned. For mixing purples what you have left are: Magenta, Process Red, Mulberry, and Raspberry pencils.

In fact, most artists tend to keep a warm and a cool of each colour on their palette.
Canary and lemon yellow are cool while school bus yellow is warm.
Azure is cool while sky blue is warm.
Forest green cool, lime green warm. etc.

That's something I can pay more attention to: whether or not a given pencil is cool or warm within the general cool or warm range it's in. I tend, naively, to treat all greens as cool, and so forth. In fact, I only recently started experimenting with mixing them since there is a huge range of straight out of the pencil colors of many different values to work with. I also only recently started muting colors by laying them on top of a bed of gray.

 

[DaveC426913]

I've only dabbled with paint, at this point anyway, and colored pencil designations are different, which makes crossover by color name problematic.

Well, these aren't paint colours, just colloquialisms. Crimson Lake is actually a Crayola colour.

I would think raspberry would be a cool red.

 

[zoobyshoe]

I was just curious to see if others could see their remotes light up.

No, I don't seem to have this experience.

You are InfraMan!

 

[DaveC426913]

So, I've posted https://www.physicsforums.com/showthread.php?t=134077" to see how many InfraPersons there are.

 

[zoobyshoe]

Well, these aren't paint colours, just colloquialisms. Crimson Lake is actually a Crayola colour.

Well, it's a mixed bag. Some colors are named for the source they're derived from:

"lake
1 a : a purplish red pigment prepared from lac or cochineal b : any of numerous usually bright translucent organic pigments composed essentially of a soluble dye absorbed on or combined with an inorganic carrier"

and others are invented labels for a hue that might be mixed from who knows what different sources.

I expect zinc white to contain zinc oxide and be consistant across manufacturers. The same for yellow ochre and its derivatives, cobalt blue, cadmium red, etc.

"Raspberry" and "Limepeel", I don't expect to be made from fruit, and am not surprised if there's an inconsistancy between two different manufacturers who both use these names for something.

 

[DaveC426913]

You might be interested in a book called https://www.amazon.com/dp/0812971426/?tag=pfamazon01-20. The author travels the world to explore the origin of colours, from the white clays in Australia to the red cochineal bugs of Brazil.

 

[zoobyshoe]

You might be interested in a book called https://www.amazon.com/dp/0812971426/?tag=pfamazon01-20. The author travels the world to explore the origin of colours, from the white clays in Australia to the red cochineal bugs of Brazil.

Sounds like exactly the kind of book that would interest me just now.

Send it to:

Mr. Z. Shoe
Zoobie Brush Shelter
Tecolote Canyon
San Diego, Ca.

 

[LHarriger]

Technically, the only necessary condition of black is "no light is emitted from it."

Why must light not be emitted?
Consider a thin film such as a bubble. The bubble does reflect light back, but undergoes a 180 phase change when reflecting off the inner surface while rays on the outer surface do not experience a phase change at all. The thinnest part of the bubble does not provide ample path length difference between waves and as a result the waves cancel causing black. So it seems to me that it is safe to say waves can leave from a substance in the direction of your eye and still result in black or am I missing something? Does the fact that their superposition results in zero truly cause the waves to no longer exist?

 

[thiotimoline]

Ok if most people say that black is an absence of colour, then is black a colour? In addition, if some light comes back to our eyes and we perceive it as a colour, then by the definition of black, no light comes back to us, hence there is no colour. By saying this, does that mean than an absence of colour = transparent?

 

[zoobyshoe]

Ok if most people say that black is an absence of colour, then is black a colour? In addition, if some light comes back to our eyes and we perceive it as a colour, then by the definition of black, no light comes back to us, hence there is no colour. By saying this, does that mean than an absence of colour = transparent?

The notion of black as a color preceeded the scientific understanding of the cause of the phenomenon of color by tens of thousands of years. It arises from the nomenclature for pigments. Primitive man, for instance, smeared himself with soot and charcoal in preparation for rituals and the color of it had specific meaning. The color had to be named to distinguish it from the white china clay he might use on a different occasion or the yellow ochre he might use on another.

We can call black a color because it's part and parcel of the in-place nomenclature for pigments.

A lady goes into a fabric store and hands the clerk a list of "colors" she needs: red, orange, black. She's making a halloween costume. Black is tacitly accepted as a proper color, no one gets upset, no one has been harmed.

Although it's nice to understand that the phenomenon of black results from the absense of the EM waves that cause the other colors, the notion of banging your head against the wall wondering if it's still proper to refer to it as a color is an obvious waste of time.

 

[arjijon]

how do you define colours?

 

[Big Bill]

No, it is still just the absence of color. If it absorbs all radiation, then it doesn't reflect any to your eyes and your eyes see nothing.

Absence of reflected light then, surely. That which does not reflect the light may be described as black. Black can have many meanings, though. Is it a wave or a particle or both? Black is certainly a colour in loose parlance, but perhaps not strictly speaking. I go for the manifestation of the absence of reflected light.

BB

 

[Ironman Joe]

If you add black to a "colour" you will change that colour. If black were not a colour, how could it change a colour? It is a matter of reflection. Black doesn't reflect any light WE can see. There are, for example, insects that can see colours we can't. Just because we can't see it, doesn't mean it's not a colour. Think about it, the only time we can't see black is when everything around a black object is black, add the tiniest bit of reflection to the surroundings, and the black object becomes visible. It's a colour, get over it.

 

[DaveC426913]

If you add black to a "colour" you will change that colour. If black were not a colour, how could it change a colour?

1] If we're talking about pigments, then most poeple agree that black is a colour. But not because of your argument. By your argument, water is a colour, since adding water to a colour, will get you a different colour too.

2] If we're not talking about pigments, and we are talking about light from an illuminated source, please demonstrate how you will (and I quote) "add black". I am not aware of any lights that emit light that is black. Are you?

It's a colour, get over it.

Don't be snotty.