What is colo(u)r?

[Saeros]

I understand that a colo(u)r is a specific wavelength of electromagnetic radiation, and that the cones in the retina in the eyes are responsible for colo(u)r processing, but what is colo(u)r? What is it that we subjectively perceive as colo(u)r? That is, what gives us the sensation of colo(u)r? Is it simply 'qualia', or is there a property inherent in a photon that gives us what we experience as colo(u)r? Also, what is the difference between hue, lightness, and saturation? are these just arbitrary distinctions, or is there actually a physical difference within the electromagnetic waves that distinguishes these three?

 

[Alice?]

I understand that a colo(u)r is a specific wavelength of electromagnetic radiation, and that the cones in the retina in the eyes are responsible for colo(u)r processing, but what is colo(u)r? What is it that we subjectively perceive as colo(u)r? That is, what gives us the sensation of colo(u)r? Is it simply 'qualia', or is there a property inherent in a photon that gives us what we experience as colo(u)r? Also, what is the difference between hue, lightness, and saturation? are these just arbitrary distinctions, or is there actually a physical difference within the electromagnetic waves that distinguishes these three?

What we percieve as 'colors' are actually electromagnetic waves that correspond with the visible light spectrum. It is speculated that we evolved over time to pick up this specific range of visible electromagnetic wavelengths because they are the most emitted wavelengths from our sun.
Here is an electromagnetic wavelength chart so you can get a better idea of what I'm talking about:
http://blogs.edf.org/climate411/wp-content/files/2007/07/ElectromagneticSpectrum.png
The cones in the eye are responsible for determining what we percieve as colors, while the rods determine the difference between light and dark.
More info on Cones and Rods: http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html
From what I know, hue is just a certain color, saturation is just the amount of color present, and lightness is the absence of color.

 

[Architectonic]

If you want to understand the process of perception, look towards the brain. The circuits involved in vision are actually quite sophisticated. But on a broader level, our perception of colour is due to repeated sensations forming and reinforcing patterns in our brains. What is interesting is when these patterns get connected to other ideas. Having a favourite colour for example, or synaesthesia.

Hue, saturation and luminance are just relative terms used to compare similar colours. There are physical (wavelength/energy) differences between these similar colours. But the display of colours together can be exploited, since our visual processing is somewhat sophisticated - see the optical illusions of colour.

 

[Saeros]

What we percieve as 'colors' are actually electromagnetic waves that correspond with the visible light spectrum. It is speculated that we evolved over time to pick up this specific range of visible electromagnetic wavelengths because they are the most emitted wavelengths from our sun.
Here is an electromagnetic wavelength chart so you can get a better idea of what I'm talking about:
http://blogs.edf.org/climate411/wp-content/files/2007/07/ElectromagneticSpectrum.png
The cones in the eye are responsible for determining what we percieve as colors, while the rods determine the difference between light and dark.
More info on Cones and Rods: http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html
From what I know, hue is just a certain color, saturation is just the amount of color present, and lightness is the absence of color.

thank you for the information
I know that what we see as color is part of the visible spectrum. The visible spectrum is just a set of wavelengths within the electromagnetic spectrum, right? So when you say that the cones determine color, they're really just seperating out different wavelengths of electromagnetic radiation, right?

you say that rods determine the difference between light and dark, but color essentially is light, isn't it? just a different wavelength. are you saying that the determine the amount of light? wouldn't a change in the amount of light just be a change in color?

The electromagnetic waves cause our qualitative experience of color, but there is, for example, no 'redness' in electromagnetic waves (there's a set of wavelengths that we perceive as red, but that isn't the same thing as our experience of red), so what is the actual sensation of 'redness'? can it be said that the object we see as being this color actually physically posesses the color as we perceive it? is the color information stored in the photons that reflect off of the object? or is the experience of redness just completely generated by our brain?

 

[walfin]

wouldn't a change in the amount of light just be a change in color?

No. Intensity does not change colour (as in hue). Photoelectric effect, remember? But it changes colour in the RGB model.

Intensity is probably value/luminance/brightness (NOT lightness). The higher the intensity (i.e. the greater the amount of light), the greater the role of the cones is as opposed to the rods (i.e. how much visual purple there is). Saturation in HSV and lightness in HSL corresponds to how white/black it is (rod perception), and hue is what is perceived by the cones.

is the color information stored in the photons that reflect off of the object? or is the experience of redness just completely generated by our brain?

You are asking what is called the "hard question" of consciousness.

The only answer I can give is, we don't know [yet].

 

[Alice?]

The electromagnetic waves cause our qualitative experience of color, but there is, for example, no 'redness' in electromagnetic waves (there's a set of wavelengths that we perceive as red, but that isn't the same thing as our experience of red), so what is the actual sensation of 'redness'? can it be said that the object we see as being this color actually physically posesses the color as we perceive it? is the color information stored in the photons that reflect off of the object? or is the experience of redness just completely generated by our brain?

I believe (key word: believe) that the concept of color is generated entirely by the brain. There is no 'red' or 'yellow' outside our minds, they are not tangible substances, there is simply the conversion of energy into something usable by our senses. Our brain picks up these electromagnetic waves through sensory organ input and translates them into a series of electical currents that move across the different parts of the brain. Bingo, color percieved. (It's not that simple of course, but I'm tired and can't find the energy to type out the whole process.)
The type of color we see depends on how much energy the wave has. Although all electromagnetic waves travel at the same speed (vacuum speed of light approx. 300,000 km/sec, I believe), they can posess different wavelengths, frequencies, and energy. 'Color' is dependent on all three of those factors within the small range of waves detectable by the human eye.

Hmm.
...Forgive me if this is scattered, it is very late. Started to answer the rest of the questions but got too sleepy. Will give this more thought tomorrow when brain is functioning at higher capacity.

For the meantime, give a look to this website I found, it has some useful info that might help you answer some of your questions:
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
Click on the bubbles to take you to different pages with more detailed information.

 

[Vrecknidj]

http://plato.stanford.edu/entries/color/

 

[Hawkeye]

http://plato.stanford.edu/entries/color/

Ironic how the whole thing was in black and white.

 

[RobdoR]

Color is a subjective experience created by the brain. It can be lost.

http://en.wikipedia.org/wiki/Cerebral_achromatopsia

The color blind painter is an interesting case. Here is a quote from the book An Anthropologist on Mars (Knopf, 1995):

"Mr. I. could hardly bear the changed appearances of people (‘like animated gray statues') any more than he could bear his own appearance in the mirror...He saw people's flesh, his wife's flesh, his own flesh, as an abhorrent gray... As the months went by, he particularly missed the brilliant colors of spring – he had always loved flowers, but now he could distinguish them by shape or smell. The blue jays were brilliant no longer; their blue, curiously, was now seen as pale gray... He could no longer see the clouds in the sky, their whiteness, or half-whiteness as he saw them, being scarcely distinguishable from the azure...
Fixed and ritualistic practices and positions had to be adopted at the table; otherwise he might mistake the mustard for the mayonnaise, or, if he could bring himself to use the blackish stuff, ketchup for jam... Red and green peppers were also indistinguishable, because both appeared black...."

 

[Saeros]

Color is a subjective experience created by the brain. It can be lost.

http://en.wikipedia.org/wiki/Cerebral_achromatopsia

The color blind painter is an interesting case. Here is a quote from the book An Anthropologist on Mars (Knopf, 1995):

"Mr. I. could hardly bear the changed appearances of people (‘like animated gray statues') any more than he could bear his own appearance in the mirror...He saw people's flesh, his wife's flesh, his own flesh, as an abhorrent gray... As the months went by, he particularly missed the brilliant colors of spring – he had always loved flowers, but now he could distinguish them by shape or smell. The blue jays were brilliant no longer; their blue, curiously, was now seen as pale gray... He could no longer see the clouds in the sky, their whiteness, or half-whiteness as he saw them, being scarcely distinguishable from the azure...
Fixed and ritualistic practices and positions had to be adopted at the table; otherwise he might mistake the mustard for the mayonnaise, or, if he could bring himself to use the blackish stuff, ketchup for jam... Red and green peppers were also indistinguishable, because both appeared black...."

I completely agree but if the sensation of color is purely a subjective experience, could it really be said that an object possesses what we call color? are objects essentially colorless? there is also no inherent property of a photon that depicts shape, or distance, or proportion, are these also subjective qualities? do objects have any properties seperate from our experience of them? do objects exist in the same way that we perceive them? or are they completely different, with unimaginable and ineffable properties?

If everything is different to how we perceive it, then it could be argued that the person from the book excerpt's view of the world is just as valid as everyone else's, no more, nor less accurate. If the person had been born with that condition, he may just have taken that view of the world as the standard, and he may not have been so disoriented at the lack of color.