Color management myths and misinformation video

[digitaldog]

Do you have any access to a "sRGB printer"? you know what I mean by that.
if you can have access to that so you can demonstrate and explain why noritsu or fuji controller are/aren't doing the transformation correctly or not.

Unfortunately I don't. But I am shocked at the difference on a print from my 3880 between ProPhoto RGB and sRGB using my Gamut test file.

[digitaldog]

Well, if we agree that color is not a physical property but a perception of our brain, then it cannot be possibly be described by a physical unit. The "volume" in this case is an abstraction.

Not sure if steping into this part of the discussion is useful or dangerous but when I asked the nice folks at CHROMIX about color volume in CT they wrote back:

The ColorThink Grapher calculates the gamut volume in terms of cubic Lab values.  A Lab value of one is one delta E (dE76 considering the way the Grapher is currently made).  So each of these cubic Lab values represent the smallest discernible color difference, and each cubic Lab value represents a unique human-discernable color. So in that sense, the larger gamut will necessarily represent more distinct, humanly-perceptable colors than a smaller gamut.   (Now that statement comes with our usual caveat that this volume number is a rough estimate, not a precise one - and it works well for and is intended for making comparisons between profiles, not for defining absolute volume numbers.)

ON the OTHER hand…..

There is a philosophical issue at stake here:  Just what constitutes a color?  Depending on how the numbers are encoded, you can have several million combinations of different numbers representing different colors in theory, but some will point out that these different number combinations do not constitute individual “colors” since they are not distinct enough to be *different* to the human vision system.

[Slobodan Blagojevic]

Well, if we agree that color is not a physical property but a perception of our brain...

Isn't everything else in the universe as well?

It took only 13 pages for our resident geeks to jump off the deepest end of the philosophy pool, into solipsism.

[digitaldog]

Isn't everything else in the universe as well?

I do not believe so. But let's not go down that new rabbit hole of yours until we know if you get the concept of gamut by staying on topic. OK?

[Slobodan Blagojevic]

I do not believe so. But let's not go down that new rabbit hole of yours until we know if you get the concept of gamut by staying on topic. OK?

Do you?

After 14 pages of this thread, and the previous 27, you still can not come up with a reasonable, succinct, plain-English definition of anything under discussion, let alone gamut.

[digitaldog]

After 14 pages of this thread, and the previous 27, you still can not come up with a reasonable, succinct, plain-English definition of anything under discussion, let alone gamut.

One you can understand? Not sure. If you spent as much time letting us know what you understand as going off topic, we might know if you have a clue about the subject or not.
 
Do you really believe you've added anything of usefulness in the previous 27 pages other than go OT, argue and mangling the lessons of gamut and color numbers it appears nearly everyone else here agrees upon (one gamut doesn't have more colors than another)? About the most salient and intelligent thing you've said here is:

Well, Andrew, I am your resident dummy, I am someone looking for "the crux of the facts," explainable in plain English, and in as few sentences as possible.

You got the facts, explained in plain English. Reply #192 on: September 01, 2014, 01:47:12 PM. A suggestion was made (« Reply #196 on: September 01, 2014, 03:47:10 PM ») concerning the ability of the eye distinguish two colors as different being limited in the yellows but is better in the greens and blues, which was added in another post.

[digitaldog]

After 14 pages of this thread, and the previous 27, you still can not come up with a reasonable, succinct, plain-English definition of anything under discussion, let alone gamut.

That you can apparently understand. You should move on then. This isn't a topic for a resident dummy, this video on the subject is apparently more your speed:
https://www.youtube.com/watch?v=6i95ZghwUf4
Oh, when he mentions muffins, ask yourself if it's blueberry or yellow corn. And does that have an affect on the gamut?

[Bart_van_der_Wolf]

It took only 13 pages for our resident geeks to jump off the deepest end of the philosophy pool, into solipsism.

Hi Slobodan,

Bringing in solipsism, which is not appropriate in the context because we are talking about a physical phenomenon common to all humans and other species, does not help the subject under discussion, of course IMHO.

The difficulty of explaining a complex subject to laymen (not used as a qualifier of intelligence, just people not educated in this field), is not a simple task. The concepts used to describe the phenomenae we percieve, e.g. as different colors is also not straight forward (differences between individuals aside).

Even if we can pin-point (which is hard enough) that there is a certain minimum difference, say a delta-E of 1 unit, needed between two colors to perceive them as being different, we're not there yet. That's because it is a relative difference in a continuous volume. So if we use a coordinate to describe those colors, we can still add e.g. 0.1 delta-E to both colors which will thus still be perceivable as different, even if the change by 0.1 is too small to perceive.

That's even before we attempt to quantify/approximate gamut volumes, and differences between them.

Your curiosity would probably also not be fully satisfied by the scientific explanation either, because that is probably in the form of physiologically-relevant colour matching functions. Hence the difficult task of translation between the scientifically correct description and the more accessible form for normal human beings.

Let's try to stay on topic, it's hard enough as it is.

Cheers,
Bart

[Slobodan Blagojevic]

... Oh, when he mentions muffins, ask yourself if it's blueberry or yellow corn. And does that have an affect on the gamut?

Of course it does!

You see, if it is a yellow corn muffin,  "the ability of the eye distinguish two colors as different being is limited in the yellows."

If it is a blueberry muffin, however, "the ability... is better in the greens and blues"

[Slobodan Blagojevic]

Hi Slobodan,

Bringing in solipsism, which is not appropriate in the context because we are talking about a physical phenomenon common to all humans and other species, does not help the subject under discussion, of course IMHO.

The difficulty of explaining a complex subject to laymen (not used as a qualifier of intelligence, just people not educated in this field), is not a simple task. The concepts used to describe the phenomenae we percieve, e.g. as different colors is also not straight forward (differences between individuals aside).

Even if we can pin-point (which is hard enough) that there is a certain minimum difference, say a delta-E of 1 unit, needed between two colors to perceive them as being different, we're not there yet. That's because it is a relative difference in a continuous volume. So if we use a coordinate to describe those colors, we can still add e.g. 0.1 delta-E to both colors which will thus still be perceivable as different, even if the change by 0.1 is too small to perceive.

That's even before we attempt to quantify/approximate gamut volumes, and differences between them.

Bart,

It wasn't me who brought solipsism into debate, I just used a proper label for what (some of) you are saying. According to some, at a certain level of abstraction, nothing is possible to define; colors do not exists, they can not be counted, differences can not be pinpointed, etc.

Your curiosity would probably also not be fully satisfied by the scientific explanation either, because that is probably in the form of physiologically-relevant colour matching functions. Hence the difficult task of translation between the scientifically correct description and the more accessible form for normal human beings...

I appreciate the difficulty, the extent of which is exemplified in the 40+ pages so far, as you are apparently failing to reach an agreement among yourselves, let alone translate it to us "normal human beings."

[digitaldog]

Of course it does!
You see, if it is a yellow corn muffin,  "the ability of the eye distinguish two colors as different being is limited in the yellows."
If it is a blueberry muffin, however, "the ability... is better in the greens and blues"

Maybe you are getting some of this despite repeated need to go OT! Progress? Perhaps.

It wasn't me who brought solipsism into debate, I just used a proper label for what (some of) you are saying.

Oh, it was the other Slobodan « Reply #262 on: Today at 09:18:00 AM »
You misunderstood what others were saying (about color). It is important to the discussion you continue to drive OT. We have numbers that define a color value. The key word here is value. That values isn't a color unless we can see it. Several others have provided examples of this with actual documents and analysis of these documents.
Let me ask you a question which is on topic and would give us some idea if you're properly following along. With a 24-bit encoding system, we can define 16.7 million color values. Does this equate to our ability to see 16.7 million colors?

[Bart_van_der_Wolf]

... According to some, at a certain level of abstraction, nothing is possible to define; colors do not exists, they can not be counted, differences can not be pinpointed, etc. ...

That's the point, it can be defined, once agreement is reached about the metrics to use, and the result is preferably understandable for laymen.

I appreciate the difficulty, the extent of which is exemplified in the 40+ pages so far, as you are apparently failing to reach an agreement among yourselves, let alone translate it to us "normal human beings."

How about this: The answer to life, the universe and everything is, ... 42. How helpful is that? Not much I would say, try again, perhaps by rephrasing the question instead of the answer. And even then, science continues to evolve with new instruments and discoveries, and new insights are gained by discussing them amongst peers. Not a useless exercise at all, but also no guaranteed outcome.

Cheers,
Bart

[digitaldog]

I appreciate the difficulty, the extent of which is exemplified in the 40+ pages so far, as you are apparently failing to reach an agreement among yourselves, let alone translate it to us "normal human beings."

We haven't failed to reach an agreement on a number of critical aspects of this discussion of gamut and color numbers. Just the opposite. That you state this illustrates you're not getting the subtle but important technical distinctions. And all of us are normal human beings. Not a single person here was born with an innate knowledge of this subject. Most of us worked quite hard to learn about it, and the 40+ pages you appear to look down on have continued to add to some of our understandings of the topic. Including you one would hope. At one point you asked if there were colors in a gamut larger than sRGB that can be used for reproduction, you got an answer. You stated wider gamut means more colors which hopefully you now know isn't the case. If wadding through 40 pages to learn just those important facts on color is too much for you and what you learned wasn't worth the effort, move on.

It is interesting your tag line says: When everybody thinks the same... nobody thinks.
Yet you complain we are failing to reach an agreement on our thinking of this subject (which isn't fully the case). Kind of inconsistent of you to make both points IMHO!

[Jim Kasson]

Bart, it doesn't have anything to do with integer or float; if you want to compute the volume of any shape its an integral over all three dimensions. To go mathematical, a triple integral of the constant function over its volume. For a cube, that simplifies to multiplying the lengths of the sides. What it is NOT is the triple integral of the delta E function, which is what is being claimed above.  That makes no sense - it's a mathematical nonsense.

Sandy, this calculation makes sense on a mathematical level, and, although I could quibble with the terminology, I don't find it too much of a stretch. Whether CIEL*a*b* is the right metric is also open to debate, but it has the advantage of familiarity. If you know the joke about the drunk looking for his keys, Lab is our lamp-post. If you don't, I need little prodding to tell it.

The details:

Lab is a 3D Cartesian space (there is also an associated cylindrical space, but that needn't concern us here). In any such space, one can compute a the volume enclosed by a closed surface, either, and you point out, through integration, or, more likely these days, through summations of the volumes of small elementary 3D solids (tetrahedra, for example) in a digital computer. The units of the volume are the product of the units of each of the three axes. If all three axes have the same unit, say, meters, we use a kind of shorthand to define the unit of the volume: rather than say meter-meter-meter, we say cubic meter.

The units of the axes in CIEL*a*b* happen to be one DeltaE apart, since sqrt(0^2+1^2+0^2) = 1, and similarly for the other two axes. Therefore, it is convenient to refer to the unit of volumes in CIEL*a*b* as cubic DeltaE.

Now, let us turn to the right metric question. CIEL*a*b* was created to describe color in a way in which perceptual differences between closely-spaced colors could be characterized as a scalar, DeltaE. There are other measures for describing other color differences, but that's not part of this discussion. If Lab were perfect for its intended purpose, discrimination ellipsoids (plots of Just Noticeable Differences, or JNDs) produced by psychologists would map to spheres in Lab. In general, they do not. There have been attempts to device color spaces that more nearly meet this criterion, and they have met with some success, but none has caught the attention of photographers like CIEL*a*b*. As an aside, Lab traditionally has been favored by color scientists working with paper and ink. Lab has a cousin, CIEL*u*v* which has been the color space of choice for color scientists working with emissive displays. The two spaces share some genetic material, notably the luminance axis. Unfortunately, Luv is not more perceptually uniform than Lab (or worse, either, although the worst errors occur in different places).

There's another problem with Lab as a metric for gamut volumes: it wasn't created to be perceptually uniform over immense color differences. There is an argument that large color differences are merely the sum of many small color differences, but I think that's dangerous thinking.

Bruce Lindbloom has produced a modification of Lab that is more perceptually uniform, and in addition, does not exhibit the perceived hue shifts along constant hue angles that Lab (and Luv) possess. There are other spaces with similar objectives. From a technical point of view, they might be better choices for gamut volume calculations, but Lab is the devil we know.

And, I think importantly, we have to keep our eyes on the prize here. Our objective in describing gamut volumes is to come up with a scalar to characterize a color space's gamut. But we need to keep in mind that that's a very crude measure of a gamut, and is not useful in most circumstances. If I'm printing an image, I want to know something about the colors in my image that the printer can't print. I don't care about the colors that aren't in my image that the printer can print. Knowing the volume of the gamut of my image and the volume of the gamut of the printer doesn't help me at all.  So why obsess on making that calculation more accurate?

[Slobodan Blagojevic]

... With a 24-bit encoding system, we can define 16.7 million color values. Does this equate to our ability to see 16.7 million colors?

Ok, let's start with that. By the way, I (the "normal human being" in Bart's terminology) am expecting an answer from you, the scientist, not the other way round. But I think the answer is: no, we can not. Which leads than to the next question:

- If we can not see them all, can we count or measure those we can, the discernible ones?

Since I think the answer will be "no" again, another question arises:

- Could it be theoretically possible that we could discern more colors in a wider space, given that "the larger gamut will necessarily represent more distinct, humanly-perceptable colors than a smaller gamut."

[digitaldog]

By the way, I (the "normal human being" in Bart's terminology) am expecting an answer from you, the scientist, not the other way round.

I'm not a scientist by training or profession.

But I think the answer is: no, we can not. Which leads than to the next question:
- If we can not see them all, can we count or measure those we can, the discernible ones?

If you understand what color is, and no, it isn't solipsism, the answer is no (the one's we can't see). Here's about as simple a sentence as I can come up with: if you can't see it, it's not a color. Can we count what we can see? Yes but how is much of the recent debate.

Could it be theoretically possible that we could discern more colors in a wider space, given that "the larger gamut will necessarily represent more distinct, humanly-perceptable colors than a smaller gamut."

The given above isn't so based on what I believe you are writing. The crux of much of the 20 odd pages here.

[Slobodan Blagojevic]

... The given above isn't so..

So, you are basically saying that the following sentence is not correct: "the larger gamut will necessarily represent more distinct, humanly-perceptable colors than a smaller gamut."

[digitaldog]

So, you are basically saying that the following sentence is not correct: "the larger gamut will necessarily represent more distinct, humanly-perceptable colors than a smaller gamut."

That is the crux of the "does a wider gamut working space have more colors than the smaller one?" Colors have to be humanly-perceptable to be considered colors and thus counted. And the recent debate is how are they counted as being humanly-perceptable. Go back to Reply #192 on: September 01, 2014, 01:47:12 PM »
Consider just one aspect of the argument of counting the colors when looking at the gamut of ProPhoto RGB alone. It contains 'colors' we can't see and thus these areas of the gamut are not humanly-perceptable. So we can't count them.

[Slobodan Blagojevic]

That is the crux...

Once again, are you saying that sentence is NOT correct?

[digitaldog]

Once again, are you saying that sentence is NOT correct?

Yes. Further, it's akin to the analogy I made about the weight of New Mexico. As Graeme said, it's wrong to talk about number of colors.