Is black a color or a lack of color? What are the characteristics that defines a color?
Is black a color or a lack of color?
That all depends on how you define color, and whether you are considering additive (e.g. you can't combine different colors of light to create light that is "black") or subtractive (e.g. you can add all of the various color pigments together to get "black") methods to reproduce color information.
What are the characteristics that defines a color?
Again, the answer to such a question totally depend upon the context in which it is being asked. Asking such a question in a physics classroom dealing with the nature of light as energy will elicit an entirely different answer than asking the same question at a paint factory. Even though each answer will be nearly a polar opposite of the other both will be correct within the context in which they are produced.
The context here at Photography.stackexchange is creative photography - not the physics of light other than as it applies to creating perceptual equivalents of the way our eye/brain systems see physical light and objects that reflect and/or absorb light.
Within the color models used by creative photography there are both additive and subtractive color models.
Inkjet and mass produced prints are subtractive - they add color to a white or near white piece of paper or other material to reduce the various wavelengths of light reflected by the paper. Each substance used to create color is a substance that absorbs some of the visible spectrum and reflects the rest, which is what we see when we look at something that is that color. If we include a substance made up of various pigments that each absorb various parts of the color spectrum, we can wind up with a substance that reflects no light in the wavelengths that we humans can perceive. Thus adding all of the different colors together makes whatever we have applied our pigments to appear black to our eyes.
CRT screens and older LCD screen that use individual pixels that emit light are additive - lack of a signal means the screen emits no light. Black is what we call the areas of the screen that aren't emitting any light.
LCD screens using a backlight are a kind of an odd mix of additive and subtractive color going on at the same time. Most newer LCD screens use a white backlight that is blocked by a color matrix that changes density depending on the amount of energy flowing through each "dot" on the screen.
As James Snell said in a comment to another answer to this question:
Black is not a lack of colour, it's a lack of luminosity/reflectance. Check out any of the perceptual colour models which split hue from brightness like HSV/HSL, Lab etc. You can specify a colour, not being able to see it does not mean it's not there any more. Put a coloured object in a completely dark room and it does not stop being coloured, you just can't see it.
When considering photographing a red apple in a dark room lit only with the very short burst of light of a flash we don't wonder what color the apple will show up as in the photo because we can't see anything except a black silhouette in the dark. We know what color the apple was before we turned the lights out. We know what color the apple will be during the near-instantaneous flash of bright light for our strobe. And we know what color the apple will be in the photo assuming our white balance is matched to the color of the flash's output. We can even know, with a fair degree of certainty, what color the apple will appear to be in our photo if we shift the white balance of the photo to other values that don't match our light source. In such a context, to say that the apple has "no color" when it sits in a room so dark that our eyes can only see a black shadow is ridiculous. The apple appears black in such a context because there is not enough luminosity to allow us to perceive the apple as red, not because it no longer has enough color for us to perceive it as red.
In the context of photography there is no current method to "reproduce" pure black. As Alan Marcus quotes a former Kodak instructor in a comment to his answer to this question:
My notes from a class lecture by Professor Ralph M. Evans @ Kodak (from years & years ago): "Black is the name given to colors that are very dark and therefore exhibit little or no hue."
Black is a color
Black is the absence of light but that is not the same as absense of color.
Color is a phisical-phisiological-perceptual-psycological-cultural interpretation of light and shadows.
Even black has some characteristics, it is the darkest unsaturated color.
You need a context
There is a chance you are not awared of black, if all you see is black, but if the color is on a context you can clearly define it as such.
This is similar to the "Actually, tomatoes are fruit, not vegetables" factoid — but even more complicated.
In plain English, black is definitely a color. You will find it very clearly defined that way in almost any dictionary. When you get a big box of crayons, it's clearly labeled 120 colors — even though black, white, and gray are surely in the mix.
Merriam-Webster's simple definition is: the dark color of coal or the night sky (emphasis added). I'll get to their more advanced definition below.
When we talk about color in a technical sense, there is some complication. We have a bunch of terms like "chroma", "hue", "saturation", "lightness", "colorfulness", and so on, and these are often used without rigorous definition. Even when there is a solid definition given, that definition can be different within different models of color — even within the single field of photography.
Merriam-Webster's entry goes on beyond the simple one, offering also: the achromatic color of least lightness characteristically perceived to belong to objects that neither reflect nor transmit light. So, even this more precise definition invokes the word "color", qualifying black as an "achromatic" one.
When someone says "black is not a color", they are probably using a particular model or concept of "color" where "color" relates only to the colorfulness or chroma (which is really just the Greek word of color, but we borrow it sometimes to make a technical distinction), separate from lightness/luminosity/value.
When someone says "black is a color!", they are using a broader definition which includes more things. If the "no it isn't!" person starts to argue with this and claims that the dictionaries are actually wrong, they are, frankly, being silly. It's okay for everyone to be right — as long as everyone understands the assumptions in play.
Oxford English Dictionary says: of the darkest colour possible, that of soot, coal, the sky on a moonless night in open country, or a small hole in a hollow object (again, emphasis added) — and adds a note which fundamentally agrees with what I'm saying in this answer overall: From a scientific perspective, the quality of being black is due to the absence or absorption of all the wavelengths of light occurring in the visible spectrum. In general use, however, it is normally classed as a colour.
Since natural language developed some hundred thousand years before we started talking rigorously about color theory, it's not surprising that English at least doesn't normally make the scientific distinction. And, since the language doesn't have great existing words for the fine details of the model, it's not surprising that we resort to somewhat awkward terms like "chroma" and "colorfulness".
In the art of photography, I don't think it's generally useful to make a split, either. If you're thinking about symbolism and cultural perceptions, it absolutely should be considered along with red, blue, purple, and whatever else. If you're talking about something technical where the distinction is useful, it can be okay, but even then, make sure you explain the model you're using. I think it's more useful to use chroma or colorfulness when that distinction is important — even if they are a little awkward.
I guess the exception I would make is when we're talking about color photography as opposed to black and white photography. Pedantry might call for me to say "no, that should be chromatic photography!" — but that seems pretty unnecessary. I think this is more a historical accident and a consequence of the lack of a common English term for the concept at issue here than it is an intentional use of a restricted sense of the world. In any case, within the context, it's clear what's meant.
Many of these terms are defined in more detail at What do Hue, Chroma, Saturation, Value, Tones, Tints, Shade, etc. mean? — this, I think, answers the second part of your question about the characteristics of color.
Light is energy. This is defined as electromagnetic waves. These energy waves are outputted by the sun, stars as well as other sources like artificial light from light bulbs etc. We also get light from emissions produced by living organisms like insects, fish. Fungi, and bacteria, this is bioluminescence. Most of the electromagnetic energy waves are invisible. We are taking about gamma rays, X-rays, and the like. We humans have evolved eyes sensitive to a narrow span of the electromagnet spectrum. Most scientist agree that the frequencies we can see, the visual portion of the spectrum, is due to the fact that the atmosphere of earth is transparent to this narrow band which spans 400 to 700 millimicrons in wave length. We cannot see those waves that are shorter or longer than this span. We can however build devices that can detect these other frequencies and convert them to something we can hear or see or otherwise display. The various colors we see each occupy a short span of the visible range. White light is a mix of all frequencies in the visible range. Black is the absence of light. We can mix red, green and blue in different amounts and make almost all the other colors. Color photography takes thee unique pictures simultaneously using only the three primary colors of red, green, and blue. This is how TV and digital phones and cameras capture and display colored pictures.
This is really a philosophy and metaphysics and psychology and all sorts of question far outside the realm of photography but to simplify it as best I can:
There are four things required for color perception to occur:
- Light to be present
- An object to reflect that light; which includes gases
- Receptors that can detect that light
- A processing system (in the case of humans that's the frontal cortex)
You can call black a color or not. By definition its more not a color than it is one. A few key points:
Color does not exist on an object. An apple is not Red, to make any claims that an apple is Red is a gross simplification. An apple has the ability to absorb all white light besides the wavelengths that most people perceive as red. But again this assumes that a white light is present or at least a light containing the wavelength most commonly perceived as red. This assumes the apple is in good health. This assumes the person or thing processing it can see that wavelength in the most commonly understood fashion. That's a lot of assumptions!
People have three types of cones and one type of rod. Except when we don't. Most people are familiar with colorblindness which is when one of the types of cones are missing or mutated. What you might not know is that there are also people with more types of cones - 4 types that we're aware of - and we have no idea how they perceive the world. See: http://www.digitaljournal.com/article/326976
So what does this have to do with black. Well one theory on the tetrachromat (person that has and can make use of the 4 cones) is that it improves dimly lit colors. But we don't know.. from that same article:
How does cDa29 see the world? She was unable to communicate her experience to the researchers in much the same way as it is impossible to describe the experience of red to a dichromatic person. Jordan says: “This private perception is what everybody is curious about. I would love to see that.”
So when is black... black? The only time that we are positive black is black is when it lacks all light. Any other time and its hard to say. Even among regular vision fatigue, the surrounding environment, old age can all diminish the ability to perceive Hue within a dark environment. For those discussing the LAB color space this is the so-called conundrum. A forest so dark that its difficult to impossible to tell if its an intensely dark green or actual black.
But we can say with certainty that black is lacking all light. Which leads us to
Is Black a Color?
Color is defined by the Cambridge Dictionary as:
- the appearance that something has as a result of reflecting light
Color is defined by the Collins Dictionary as:
- the sensation resulting from stimulation of the retina of the eye by light waves of certain lengths
Color is defined by Merriam-Webster dictionary as:
- a : a phenomenon of light (as red, brown, pink, or gray) or visual perception that enables one to differentiate otherwise identical objects
So the real question, and the only question is:
Can we call the complete lack of light a sensation on the retina?
Most would say no. But then again when we're so used to light being present, perhaps removing it all is a feeling. I've been in an unlit cave where you get as close to black as possible - it is a strange feeling. I'm not sure that qualifies though. I wouldn't call it such. It certainly doesn't help you differentiate objects.
Is Black a lack of color?
Black is absolutely a lack of color. Color is a stimulus upon the retinas, black is when there is no stimulus.
In practical application: This is pretty irrelevant. Language is for understanding each other and most don't know or care enough to distinguish such intricacies. As long as you know what you're talking about and others know what you're talking about the rest is irrelevant. When you need to get into technical things such as philosophy and physics than it becomes important. In photography --- not so much.
Update with new question from Mattdm in comments
"It certainly doesn't help you differentiate objects." So, if there are three objects, one blue, one red, and one black, and I ask you to pick up the black one, you wouldn't be able to do it?"**
Yes and no. Like I said most of the time our English and assumptions of the world take over and most of the time are right. You're basing it on your own prior knowledge and perception of redness, blueness, and blackness.
I'm reminded of going to a suit store and the guy swearing to me the suit was black while my years of experience in color told me it had blue in it. Was I right or was he? I am more right but for most purposes he can still call it black and its understood as such. But it absolutely had blue in it. In fact let's see an image:
All of these were sampled from a single photo of guys in suits. If I ask you to hand me the black one or black ones would you easily be able to? I doubt it. This is why a suit is more expensive than individual sports coats and slacks. A suit must be sold together made of the exact same piece and segment of fabric in order to match. A black sports coat from one shop and black slacks from another are likely to be two entirely different "blacks". None of which are pure black.
Again, this is a question of semantics and what effect a lack of stimulus has on your vision - if any. And a philosophical inquiry as to whether we can fully trust our senses. Nearly every theory on color says it doesn't exist outside of the brain (processor).
I'd encourage anyone interested in this subject to study it. Here are two wonderful videos (all hosted on YouTube at time of posting) to get you started:
Visible light is part of the electromagnetic spectrum, our eyes can perceive only a small fraction of this spectrum, from black to white... the lack of light or poor light is perceived as black.
Our eyes can differentiate colors when there is the right amount of light, on very poor light conditions our eyes perceive only a shade of gray colors, this is because of our anatomy:
While using a small telescope to watch far away objects, you'll see this objects as "black and white" or "gray" but this is mainly because you are receiving a poor quantity of light, using a big telescope can give you more light and more colorful images, astronomy enthusiast on a small budget use long exposure photography to capture more light and have more colorful images, al this examples show that black is the perception of low light or not light at all.
Since in photography black is never the absolute black, I would say that for purposes of us photographers and color management enthusiasts, the black is a color.
If you think black is not a color, remove it from your vocabulary when speaking about photography and color management and see what happens...