Colour?

[Gareth56]

Is black a colour?

[ajb]

Yes, as colour is by definition what the human eye perceives.

 

In a physics context you mean "what wavelength/frequency is black-light?"

 

Answer any the eye cannot see as another colour. I.e. anything outside of the visual spectrum.

[insane_alien]

nope it is the absence of colour. white is the opposite with all the colours present.

 

though it does depend on which definition of colour you use. certainly in the most widly used sense, black is a colour as in 'it's coloured black'. artists will tell you its a shade and scientists will say it is the absence of colour.

[ajb]

nope it is the absence of colour. white is the opposite with all the colours present.

 

though it does depend on which definition of colour you use. certainly in the most widly used sense, black is a colour as in 'it's coloured black'. artists will tell you its a shade and scientists will say it is the absence of colour.

 

Indeed my artist wife insists it is a shade! (could not get a good definition of what colour is from her, but she gave plenty of examples).

 

I think colour is really a psychological idea and not a physics one.

[Gareth56]

But if colour is described by the frequency of the radiation e.g. red is around 400nm and as such when this frequency of radiation impinges on the cones at the back of the eye is causes chemical changes in those cells; so I would suggest that colour perception is a physiological one also some people are colour blind in that they cannot perceive certain colours.

 

I understood it that black was considerd to be the absence of colour hence the eye doesn't perceive any colour because all the frequencies of [visible] light are absorbed by the object, ergo, black is not a colour.

[Klaynos]

But if colour is described by the frequency of the radiation e.g. red is around 400nm what frequency does the "colour" black equate to.

 

But it doesn't really because the human eye doesn't detect all wavelengths, and certainly not all at the same quantum efficiency.

[ajb]

Klaynos agrees with me!

 

Colour is in the mind, it is how your brain interprets the frequency of the light. Any frequencies you cannot "see" are black.

[Gareth56]

But it doesn't really because the human eye doesn't detect all wavelengths, and certainly not all at the same quantum efficiency.

 

I agree, the human eye cannot detect all wavelengths otherwise we would see the sky as being more purple than blue and also wouldn't require night vision goggles to see objects at very low light levels!

 

Klaynos agrees with me!

 

Colour is in the mind, it is how your brain interprets the frequency of the light. Any frequencies you cannot "see" are black.

 

It's how the brain interprets the result of the interaction of the radiation with the molecules (via electronic transitions) within the cones located at the back of the eye.

[swansont]

Indeed my artist wife insists it is a shade! (could not get a good definition of what colour is from her, but she gave plenty of examples).

 

I think colour is really a psychological idea and not a physics one.

 

I think the physics answer is no and the art answer is yes. In physics you'd have to be able to assign a wavelength or spectrum to it. What does the spectrum of "black" look like?

[insane_alien]

What does the spectrum of "black" look like?

 

[hide]like this[/hide]

[ajb]

I think the physics answer is no and the art answer is yes. In physics you'd have to be able to assign a wavelength or spectrum to it. What does the spectrum of "black" look like?

 

Is that the "physics" definition of a colour, an assignment of a wavelength?

 

So infra-red (whatever wavelength that is) is a colour even though we cannot see it?

[Klaynos]

Is that the "physics" definition of a colour, an assignment of a wavelength?

 

So infra-red (whatever wavelength that is) is a colour even though we cannot see it?

 

That's what I'd say...

 

Colours are used to name bands in the same way as infrared, microwave or THz...

[Jacques]

I think the physics answer is no and the art answer is yes.

The art answer is also no. From the point of view of an artist black is the absence of color or a shade.

[swansont]

The art answer is also no. From the point of view of an artist black is the absence of color or a shade.

 

But surely you can purchase black paint.

[ydoaPs]

The art answer is also no. From the point of view of an artist black is the absence of color or a shade.

 

I thought that was the physics answer. Isn't a "blackbody" a system which radiates or absorbs no EM radiation?

 

I thought the art answer is black is ALL COLOURS.(Get a bunch of paint and mix it together)

[insane_alien]

a balckbody is a perfect absorber and emitter. YDOAPS

[ydoaPs]

a balckbody is a perfect absorber and emitter. YDOAPS

oops, Did I mention I'm "slightly" stupid?

[insane_alien]

and you get to tinker with nuclear reactors?

[Phi for All]

oops, Did I mention I'm "slightly" stupid?

Don't be so hard on yourself.

 

 

 

That's what we're here for.

[ydoaPs]

and you get to tinker with nuclear reactors?

 

Makes ya feel safe, don't it?

[gisburnuk]

Colour is the mind's interpretation of visualising the electrical inpulses received from the frequencies htting the receptors.

The absence of light also induces colour, since this creates the colour black, but this is what the mind creates.

What we see isn't true reality, what we hear isn't true reality. What we taste isn't true reality, our mind translates the outside physics into something we can interpret.

 

I wonder whether blind people with a brain related disorder see colour?

[ydoaPs]

I wonder whether blind people with a brain related disorder see colour?

 

Depending on the type of blindness, it would be possible if they had synesthesia.