When I say, “that object is red”, I mean it as shorthand for “that object has a reflectance, transmittance, and emittance profile that usually leads humans to experience a red color sensation when viewing the object in neutral-ish conditions”.
You could mean that.
Or you could mean it as shorthand for “that object emits or reflects electromagnetic radiation with a pronounced peak around 700nm wavelength”.
Neat, I recognize your username. I always liked your choice of username, and I’ve often enjoyed your comments. Thanks.
you could mean it as shorthand for “that object emits or reflects electromagnetic radiation with a pronounced peak around 700nm wavelength”.
Except that is not sufficient nor necessary to ensure that the object would typically generate a red color sensation in humans, even in “neutral or typical conditions”. So, I would not mean it as shorthand for that. Color sensations can not be boiled down to or predicted by spectral power distributions and reflectance profiles only.
I’m thinking your comment perhaps was a gentle nudge to say, “it’s not too hard to make color an objective creature”. Well, you can come up with some objective definition of whether some object has the property of redness, but you’d have to basically reimplement the human visual system and assume a huge amount about the object’s current surroundings (or you could not go to that effort and end up with something that does a very poor job of corresponding to human color sensations). It would be similar to converting bitterness of food or soothingness of music into objective properties. Or maybe your comment was a gentle nudge in a completely different direction.
that is not sufficient nor necessary to ensure that the object would typically generate a red color sensation in humans
You are now dealing in circular logic. If you criterion for “red” is a “color sensation in humans”, you have already defined red. That’s it, we’re done. My point is that you do not have to define “red” in terms of human qualia.
Definitions should be judged by their usefulness. Sometimes “a human would call that red” is the right defintion, sometimes “this light peaks at ~700nm” is the right definition. For example, if the sensor in your telescope captured a few photons from a dim distant star, you might call them “red” even if the human visual system will be unable to process these photons (or associate with them the qualia of “red”).
it’s not too hard to make color an objective creature
It is easy to make color an objective creature—just define it a particular mixture of wavelengths of visible light. To produce a workable definition of subjective color is much harder—this is a practical matter in photography and graphics and whole books are written on the subject.
You are now dealing in circular logic. If you criterion for “red” is a “color sensation in humans”, you have already defined red. That’s it, we’re done.
We would run into the same problem for any description of a quale/sensation. For example, we would describe/identify nausea, bitterness, and redness in similar ways—it’s hard to directly describe sensations, so we often indirectly identify sensations by pointing to conditions that lead to humans experiencing the sensation, or pointing to how the sensation relates to other sensations. That’s the unfortunate business of qualia/sensations.
So, the criterion isn’t circular, it’s just unsatisfying in that we basically end up saying, “in situation X, you will probably feel the sensation I’m talking about, and we’ve labeled that sensation ‘red’”.
Definitions should be judged by their usefulness.
Agree 100%. Sometimes you can pretend that color is a simple objective creature and it turn out okay, just like we can use Newtonian physics when relativistic effects are small enough for our purpose.
just define it [color] a particular mixture of wavelengths of visible light
As I said before, you CAN come up with a simple objective definition of color, but it will do a “very poor job of corresponding to human color sensations”.
A particular spectral power distribution can lead to many different color sensation depending on visual context, and even the expectation and memory of the human experiencing the color sensation. This fact makes that sort of definition unfit for a lot of purposes.
Look at these two scenes. The left-hand scene contains “blue” pixels that use the same RGB value (0x6e6f73) as the right-hand scene’s “yellow” pixels. And in the context of the legend at top, that RGB value produces a third color sensation: gray.
So, any definition of color that only depends on spectral power distributions will not correspond very well with actual human color sensations. The linked picture demonstrates that “the light mixture your monitor produces for an RGB value of 0x6e6f73” is nowhere near enough information to predict what color sensation a human will experience from viewing pixels with that RGB value, even within the limited range of conditions of looking at something on a monitor.
Also, the two-scene picture is not an unusual case. The highly contextual nature of color perception is ubiquitous. Human color processing is always making contextual adjustments from scene illumination. The picture of a fruit basket in this section does a good job of showing how contextual adjustments are the norm. The overwhelming importance of context in color perception massively shrinks the situations where simple objective definitions of color are useful. Treating color as a simple objective creature gets you into trouble fairly quickly.
To produce a workable definition of subjective color is much harder—this is a practical matter in photography and graphics and whole books are written on the subject.
Yep, which is why I urged the author of the post to choose something other than color as an example of a simple/natural category.
Also, don’t you mean objective? The color model work you’re talking about is an effort to come up with objective mathematical models that exist outside of human minds (thus considered objective) that give outputs that correspond to sensations that exist inside human minds (those sensations being subjective). I don’t want us to get hung up on what “objective” and “subjective” means, but if this conversation continues much more, it might be good to spend a bit of time making sure we understand each other when we use those words.
We would run into the same problem for any description of a quale/sensation.
Only if you decide you’re defining a sensation and not some physical phenomenon.
The highly contextual nature of color perception is ubiquitous. Human color processing is always making contextual adjustments from scene illumination.
Yes, I understand that very well. But all that tells you is that different definitions will diverge in many cases.
Also, don’t you mean objective?
“Subjective” was probably the wrong word. I distinguish:
A physical approach which defines color through spectral power distributions
A human objective approach which defines color via the tristimulus model (the CIE color space, etc.)
A human subjective approach which defines color as a particular perception
The human subjective approach has—as you have pointed out—all the issues associated with talking about subjective sensations, that is, they are essentially unobservable and it’s very hard to get a good handle on them. That, to me, makes defining color through qualia a definition that isn’t useful all that often.
Only if you decide you’re defining a sensation and not some physical phenomenon...That, to me, makes defining color through qualia a definition that isn’t useful all that often.
That’s the definition used in the overwhelming majority of cases. Careful, technical texts often make it clear that color is a sensation. Even Isaac Newton stressed that “the rays [of light] are not colored”.
Even wikipedia goes with the sensation definition of color: “Color...is the visual perceptual property corresponding in humans to the categories called red, blue, yellow, etc...The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain.”
In everyday use, when a person says things like “hand me the blue towel”, that person usually does not care, know, or even think about reflectance profiles and spectral power distributions. Usually all that person cares about is that the towel “looks blue” to him and the person he’s talking to. He’ll say “that towel is blue” just like he’ll say “that chocolate is bitter”.
It’s very useful to have definitions that depend on human sensations. You and I are both humans, and we often have conversations with other humans.
You could mean that.
Or you could mean it as shorthand for “that object emits or reflects electromagnetic radiation with a pronounced peak around 700nm wavelength”.
Neat, I recognize your username. I always liked your choice of username, and I’ve often enjoyed your comments. Thanks.
Except that is not sufficient nor necessary to ensure that the object would typically generate a red color sensation in humans, even in “neutral or typical conditions”. So, I would not mean it as shorthand for that. Color sensations can not be boiled down to or predicted by spectral power distributions and reflectance profiles only.
I’m thinking your comment perhaps was a gentle nudge to say, “it’s not too hard to make color an objective creature”. Well, you can come up with some objective definition of whether some object has the property of redness, but you’d have to basically reimplement the human visual system and assume a huge amount about the object’s current surroundings (or you could not go to that effort and end up with something that does a very poor job of corresponding to human color sensations). It would be similar to converting bitterness of food or soothingness of music into objective properties. Or maybe your comment was a gentle nudge in a completely different direction.
Thanks :-)
You are now dealing in circular logic. If you criterion for “red” is a “color sensation in humans”, you have already defined red. That’s it, we’re done. My point is that you do not have to define “red” in terms of human qualia.
Definitions should be judged by their usefulness. Sometimes “a human would call that red” is the right defintion, sometimes “this light peaks at ~700nm” is the right definition. For example, if the sensor in your telescope captured a few photons from a dim distant star, you might call them “red” even if the human visual system will be unable to process these photons (or associate with them the qualia of “red”).
It is easy to make color an objective creature—just define it a particular mixture of wavelengths of visible light. To produce a workable definition of subjective color is much harder—this is a practical matter in photography and graphics and whole books are written on the subject.
We would run into the same problem for any description of a quale/sensation. For example, we would describe/identify nausea, bitterness, and redness in similar ways—it’s hard to directly describe sensations, so we often indirectly identify sensations by pointing to conditions that lead to humans experiencing the sensation, or pointing to how the sensation relates to other sensations. That’s the unfortunate business of qualia/sensations.
So, the criterion isn’t circular, it’s just unsatisfying in that we basically end up saying, “in situation X, you will probably feel the sensation I’m talking about, and we’ve labeled that sensation ‘red’”.
Agree 100%. Sometimes you can pretend that color is a simple objective creature and it turn out okay, just like we can use Newtonian physics when relativistic effects are small enough for our purpose.
As I said before, you CAN come up with a simple objective definition of color, but it will do a “very poor job of corresponding to human color sensations”.
A particular spectral power distribution can lead to many different color sensation depending on visual context, and even the expectation and memory of the human experiencing the color sensation. This fact makes that sort of definition unfit for a lot of purposes.
Look at these two scenes. The left-hand scene contains “blue” pixels that use the same RGB value (0x6e6f73) as the right-hand scene’s “yellow” pixels. And in the context of the legend at top, that RGB value produces a third color sensation: gray.
So, any definition of color that only depends on spectral power distributions will not correspond very well with actual human color sensations. The linked picture demonstrates that “the light mixture your monitor produces for an RGB value of 0x6e6f73” is nowhere near enough information to predict what color sensation a human will experience from viewing pixels with that RGB value, even within the limited range of conditions of looking at something on a monitor.
Also, the two-scene picture is not an unusual case. The highly contextual nature of color perception is ubiquitous. Human color processing is always making contextual adjustments from scene illumination. The picture of a fruit basket in this section does a good job of showing how contextual adjustments are the norm. The overwhelming importance of context in color perception massively shrinks the situations where simple objective definitions of color are useful. Treating color as a simple objective creature gets you into trouble fairly quickly.
Yep, which is why I urged the author of the post to choose something other than color as an example of a simple/natural category.
Also, don’t you mean objective? The color model work you’re talking about is an effort to come up with objective mathematical models that exist outside of human minds (thus considered objective) that give outputs that correspond to sensations that exist inside human minds (those sensations being subjective). I don’t want us to get hung up on what “objective” and “subjective” means, but if this conversation continues much more, it might be good to spend a bit of time making sure we understand each other when we use those words.
Only if you decide you’re defining a sensation and not some physical phenomenon.
Yes, I understand that very well. But all that tells you is that different definitions will diverge in many cases.
“Subjective” was probably the wrong word. I distinguish:
A physical approach which defines color through spectral power distributions
A human objective approach which defines color via the tristimulus model (the CIE color space, etc.)
A human subjective approach which defines color as a particular perception
The human subjective approach has—as you have pointed out—all the issues associated with talking about subjective sensations, that is, they are essentially unobservable and it’s very hard to get a good handle on them. That, to me, makes defining color through qualia a definition that isn’t useful all that often.
That’s the definition used in the overwhelming majority of cases. Careful, technical texts often make it clear that color is a sensation. Even Isaac Newton stressed that “the rays [of light] are not colored”.
Even wikipedia goes with the sensation definition of color: “Color...is the visual perceptual property corresponding in humans to the categories called red, blue, yellow, etc...The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain.”
In everyday use, when a person says things like “hand me the blue towel”, that person usually does not care, know, or even think about reflectance profiles and spectral power distributions. Usually all that person cares about is that the towel “looks blue” to him and the person he’s talking to. He’ll say “that towel is blue” just like he’ll say “that chocolate is bitter”.
It’s very useful to have definitions that depend on human sensations. You and I are both humans, and we often have conversations with other humans.
I do not believe that to be so. An example: all color management in digital photography. Another example: color swatches (e.g. Pantone).