attention color whizes: non-typical sRGB/RGB/ProPhoto question

[tgray]

The question was less directed towards color science and more towards implementation in current products or tools that use these profiles. Its one thing to enter numeric values in web based color calculator or go about making graphs that purposely ignore the adaptation. But can we do this in the current tools we use to convert color spaces using these profiles? If not, there’s probably a reason why.

Who are those current products marketed at?  I'm guessing, for 99% of practical purposes, photographers and people in industries who need to deal with color don't care about these 'numbers', thus those products probably don't implement those features (or bury them out of the way).  They want to translate from one color space to another, without throwing colors away, keeping them as perceptually as close as possible.  Again, that doesn't mean that it's not interesting to talk about other cases and possibly even relevant.

Secondly, with respect to that web calculator - what do you think these applications you speak of are doing?  They are just manipulating numbers for you...

If we tossed out all research that the general public didn't find 'useful', we would have only a fraction of the technology and knowledge we have now.

[joofa]

Exactly ….

Joofa, you need to give the name and phone number of the girl to digitaldog he is correct…

Hi Manuel,

As Iliah has noted there are several inaccuracies and misunderstandings in Digital Dog's note. A small thread can be done on them. But, in this thread I'm not prepared to go into them. Otherwise, it needs to be corrected.

Sincerely,

Joofa

[digitaldog]

> wasn't expecting so much.
You must be joking.
It was very, very basic, and it needs some rephrasing for accuracy.

By all means, please do so.

[digitaldog]

Who are those current products marketed at?  I'm guessing, for 99% of practical purposes, photographers and people in industries who need to deal with color don't care about these 'numbers', thus those products probably don't implement those features (or bury them out of the way).

So products that don’t produce practical purposes are ideal for conversions that don’t implement adaptation and thus, comply with Joofa’s findings? Talk about a solution in search of a problem. Seems this adaptation is useful, expected and designed for a purpose.

I suppose a car manufacture could make the brake pedal accelerate the vehicle and the gas pedal make it slow down, but there’s hardly a reason to do so. I suppose Adobe could alter the math in Phtooshop so it does the opposite of what the UI tells us to expect, but there’s hardly a reason to do so. This entire exercise of Joofa’s has as yet, proven no real world usefulness. The math may be correct, I don’t know and until he provides it to readers here like Mark that do and have asked for it, its a moot point. But when the rubber hits the road, at least as far as I know (and I’ve asked often), what he proposes to illustrate just doesn’t happen expect as a theoretical exercise. What’s the point?

[digitaldog]

It is akin to saying "There are brightnesses we can see, but the camera can't capture those"

Well brightness is a human perception, it is subjective. There are brightnesses we can see, the camera can't capture. Lightness is a property of a color space, which is defined in a way to reflect the subjective brightness perception (of a color) for us humans.

[tgray]

So products that don’t produce practical purposes are ideal for conversions that don’t implement adaptation and thus, comply with Joofa’s findings? Talk about a solution in search of a problem. Seems this adaptation is useful, expected and designed for a purpose.

I suppose a car manufacture could make the brake pedal accelerate the vehicle and the gas pedal make it slow down, but there’s hardly a reason to do so. I suppose Adobe could alter the math in Phtooshop so it does the opposite of what the UI tells us to expect, but there’s hardly a reason to do so. This entire exercise of Joofa’s has as yet, proven no real world usefulness. The math may be correct, I don’t know and until he provides it to readers here like Mark that do and have asked for it, its a moot point. But when the rubber hits the road, at least as far as I know (and I’ve asked often), what he proposes to illustrate just doesn’t happen expect as a theoretical exercise. What’s the point?

Look, I don't want to be confrontational, but your whole argument is essentially, "I don't find it useful, thus it's pointless."  Let me say this loud and clear: I DON'T KNOW THE IMPLICATIONS OF JOOFA'S STATEMENT.  That doesn't mean it's not useful.

I don't think joofa's argument is supposed to be practically applied in 100% of situations.  He's stated repeated that it's under a specific set of circumstances.  If those circumstances aren't applicable to you, then why worry about it?

And let me call out this specific statement:

Seems this adaptation is useful, expected and designed for a purpose

That does not equal, "Seems this adaptation is useful, expected and designed for ALL purposes."  There's a difference there.  I'm not in the industry, but I would think that chromatic adaptation/relative colorimetric conversions (are they the same things?) are what you want most of the time.  So I'm guessing that's what the software does.  To use the analogy of language, most of the time we want to translate for meaning and intent, not verbatim preserving word order.  That doesn't meant that a verbatim translation preserving word order and mangling meaning and intent isn't useful...

[Iliah]

> Well brightness is a human perception

Like in HSB?

[ejmartin]

From The Reproduction of Colour by R.W.G. Hunt (an excellent text btw)

Mark, I don't understand his point at all.  What on earth difference does it make that there is overlap in the spectral responses, as long as they are independent functions?

[digitaldog]

Look, I don't want to be confrontational, but your whole argument is essentially, "I don't find it useful, thus it's pointless."

I never said its useless, I asked the why the use and more importantly, what product provides the use! No one so far has answered either question. Kind of telling.

[broch]

> There are colors we can see, but the camera can't capture

"Can't capture" is not an exect term here. It is akin to saying "There are brightnesses we can see, but the camera can't capture those"

From physiology point of view you are wrong. In general one would consider camera sensor as color blind. You are mixing/believing that S, M, L cones means three pure colors. Humans (males) can distinguish four perceptually unique colors (pure means without mix of any other hue): RGBY.
Camera sensor has only three pure colors RGGB.

[Iliah]

> From physiology point of view you are wrong.
I said "can't capture" is not an accurate term here. Camera captures everything in visible light that is below saturation point and above noise floor.

> Camera sensor has only three pure colors RGGB.
Yes, if yellow is pure green, or two unequal greens (Adobe recently joined the club adopting the strategy to deal with g1 non equal g2) plus something remotely r and remotely b make for 3 pure colours.

[Graystar]

Right.  And what he's failing to realize is that those cases have no meaning whatsoever

Again, I'm not knowledgeable enough in color science to answer that question.  I'm guessing though that, "those cases have no meaning whatsoever" is not true.

If you're not knowledgeable enough to answer, then why are you even taking guesses?

It's probably safer to say that, "those cases have no meaning in most practical usage scenarios."  That doesn't mean that it's not interesting and perhaps even relevant to think about.

Probably safer for someone who is not knowledgeable enough to answer, but for everyone else, it’s important to not have meaningless jumbles of numbers touted as proof of something that’s not correct.

[digitaldog]

> Well brightness is a human perception
Like in HSB?

No, like HSL!

[Iliah]

No, like HSL!

Can't find HSL in Photoshop Info palette, sorry.

[tgray]

I never said its useless, I asked the why the use and more importantly, what product provides the use! No one so far has answered either question. Kind of telling.

What's it telling about?  Just that it's not been applied yet (as far as we know in this discussion).

No offense to joofa, but I'm guessing his statement is nothing new.  I would imagine it is well known to the color scientists working behind the scenes.  They know when it is applicable and when it isn't.

I once went to talk by one of the physicist/graphics gurus who works at Dreamworks.  He gave a presentation on new physics models they were implementing for Shrek 3.  I had some questions for him after the talk which were relevant to my research.  I'm not in entertainment; I wanted physical accuracy at all costs.  I asked my questions and he laughed and said something along the lines of, "Yeah, that's the right way to do it, but we don't do that.  We do something that the artists decided looks good enough and is significantly faster to implement, but it's not physically accurate."  Just because something is put into practice is not a referendum on it's validity, accuracy, or desirability.  It just means that it's been put into practice.

I'm guessing joofa is from an academic/research background.  If so, he's probably used to finding interesting questions/facts and following them to their logical conclusions.  Sometimes those conclusions are relevant, sometimes not.

[broch]

> From physiology point of view you are wrong.
I said "can't capture" is not an accurate term here. Camera captures everything in visible light that is below saturation point and above noise floor.

> Camera sensor has only three pure colors RGGB.
Yes, if yellow is pure green, or two unequal greens (Adobe recently joined the club adopting the strategy to deal with g1 non equal g2) plus something remotely r and remotely b make for 3 pure colours.

no,
camera Yellow is not pure obviously. Proper setup would be Red sensor, Green sensor Blue sensor and Yellow sensor. Currently Yellow is achieved by color mixing. Not the same thing.
I am talking about experimental models. What you seem to assume is that S, M, L cones can respond to three pure colors. That is wrong assumption.
You have also other problems that definitely are beyond the scope of original topic.

[Iliah]

Yes, creating illusions is how it works, be it cartoons or fantasy. Chromatic adaptation can be viewed as creating an illusion, but used unproperly it destroys the illusion. Sometimes chromatic adaptation is for the sake of art, but sometimes it is just meaningless pseudo-physical accuracy and numbers.

[tgray]

If you're not knowledgeable enough to answer, then why are you even taking guesses?

I'm not sure anyone in this thread is REALLY knowledgeable enough to talk about it  I'm not trying to claim I'm an expert.  Are you?  I do think I have the background and training to think about tough problems that I'm not necessarily intimately familiar with though.  I try to approach them with an open mind and not try to be too dogmatic about my position.  So I say things like, "I'm not familiar enough with to answer that question," or "I'm not an expert."  Which means I'm open to discussion.  It doesn't mean that I'd attack people with comments like, "Why are you even taking guesses?"

Bruce Lindbloom, the one expert that people seem to agree on is actually an expert, seems to back up what joofa is saying, with the limited set of conditions that agree with what joofa posited at the beginning.

[Iliah]

> camera Yellow is not pure obviously.
Have you ever looked at some CFAs directly? In that case you might have seen that what is commonly called green component of a Bayer array is yellow in fact. And you somehow ignored "two different greens" problem, or are we back to dividing by zero and coming with 4=3?

[Iliah]

> I'm not trying to claim I'm an expert.  Are you?

Yes, he does claim he is an expert, and even came up with a groundbreaking statement in this thread, saying white point in XYZ is 1,1,1.