"Color science" vs RAW

J A C S said:

I do not disagree in general with most of what you said but I want to comment on those suggestions:

J A C S said:

1. Measure a CFA spectrogram for the IQ3 trichromatic and show that in reality P1 doesn't actually have a trichromatic CFA installed, and/or...

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If somebody has it, I would be curious to see it in comparison with a popular camera, done by the same tester. We have to be careful though - eyeballing the curves may show differences (there are always some differences) but evaluating their significance is not an easy task.

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Agree. Based on the variance we've seen in the measured CFA spectrograms posted here over the years it would be good to see measurements of an IQ3 Trichromatic next to another popular camera from the same tester with same method to help to normalize the result.

J A C S said:

J A C S said:

2. Test the IQ3 trichromatic camera against a standard camera with a set of subjects that typically invoke metameric failure and show that in reality there's no difference in the color performance between either.

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Again, one ahs to be cautious here: most randomly chosen cameras would have differences but then the visual results depend on the processing as well. Metameric failure, IMO, is everywhere, maybe subtle. My ultimate test would be a long term use (I still do not know enough about my 8 month old camera) but since this is hard to do, comparisons would be interesting to see.

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True. Metameric failure is also lighting dependent which makes it even harder to reproduce outside of a controlled environment.

Still, I personally try to save items that I see have caused metameric failure in the past just to use for testing my own cameras. Hopefully I'm not the only one so fussy on color to do so, lol.

fPrime

--
Half of my heart is a shotgun wedding to a bride with a paper ring,
And half of my heart is the part of a man who's never truly loved anything.

fPrime said:

Iliah Borg said:

fPrime said:

I've already given you the next challenge

Overcome the IQ3 trichromatic CFA sensor with measurement against a non-trichromatic CFA

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I don't see your own data to challenge it.

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Why should I?

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Think of what you just said. "Why should I?" Why should you what?

Only data can be challenged. No data - no challenge. You have no data, so you have no challenge.

More importantly, why are you changing the subject? I'm saying, "looser" filters bring nothing worthy in the end, nor "lower noise", nor "higher resolution". Nothing to do with IQ3 trichromatic.

fPrime said:

I'm aligned with Phase One's published point of view.

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You are not. You said, "looser CFA's for higher resolution":


Are folks at Phase One saying IQ3 trichromatic has lower resolution and people getting it are at resolution disadvantage? Do you think Phase One marketing agree with you on that one?

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Jack Hogan said:

Jack Hogan said:

fPrime wrote: ... 2. Test the IQ3 trichromatic camera against a standard camera with a set of subjects that typically invoke metameric failure and show that in reality there's no difference in the color performance between either.

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If there is a difference in the CFAs, as is implied by your thought experiment, then it's guaranteed that there will be differences in the color performance of the cameras. The question is, which will produce the better color? And once we define the context and what better color means we might have a quantitative answer, for that particular setup.

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Granted. Better here shouldn't be a measurement of more pleasing color but rather simply more accurate color.

And in that vein, this is why I also suggest subjects with color hues that routinely induce metameric failure in common lighting conditions. Ideally it's an obvious failure too, not a subtle one. In their trichromatic marketing material it’s clear some of P1’s favorite test material includes chocolate, coffee beans, salmon, etc., but I personally notice more metameric failure around purples and greens.

fPrime

--
Half of my heart is a shotgun wedding to a bride with a paper ring,
And half of my heart is the part of a man who's never truly loved anything.

Jack Hogan said:

Jack Hogan said:

fPrime wrote: ... 2. Test the IQ3 trichromatic camera against a standard camera with a set of subjects that typically invoke metameric failure and show that in reality there's no difference in the color performance between either.

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If there is a difference in the CFAs, as is implied by your thought experiment, then it's guaranteed that there will be differences in the color performance of the cameras. The question is, which will produce the better color? And once we define the context and what better color means we might have a quantitative answer, for that particular setup.

Jack

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You know, when folks start to illustrate spectral response using MaxMax plots ("Each picture /IB: and they mean OOC JPEGs here/ was opened in Photoshop and the RGB raw values were compiled. Using our adjustment table, we adjusted the raw RGB values to create the adjusted spectral response curve shown below", see https://maxmax.com/spectral_response.htm ), like Doug did here, https://forum.luminous-landscape.com/index.php?topic=121132.msg1006648#msg1006648 - bets are off.

The discussion stops making sense, because, for example, one party is discussing some out-of-the-box colour transforms and follow marketing claims; while the other party is discussing limits of colour transforms' optimizations, including limits induced by different CFA formulations - and (sacrilege!) tend to discuss those "by the numbers".

--
http://www.libraw.org/

Iliah Borg said:

The discussion stops making sense, because, for example, one party is discussing some out-of-the-box colour transforms and follow marketing claims; while the other party is discussing limits of colour transforms' optimizations, including limits induced by different CFA formulations - and (sacrilege!) tend to discuss those "by the numbers".

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The discussion still makes sense as a practical matter, which is the whole point.

Iliah Borg said:

fPrime said:

Iliah Borg said:

fPrime said:

I've already given you the next challenge

Overcome the IQ3 trichromatic CFA sensor with measurement against a non-trichromatic CFA

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I don't see your own data to challenge it.

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Why should I?

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Think of what you just said. "Why should I?" Why should you what?

Only data can be challenged. No data - no challenge. You have no data, so you have no challenge.

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Ok but the challenge subject here isn't data that I have nor even data that P1 has published. The subject is entirely P1's characterization of why and how CFA's were weakened. If you want to challenge their determination on this then I'm suggesting a straightforward method to do so. Simply disprove the existence or utility of their trichromatic CFA.

Iliah Borg said:

More importantly, why are you changing the subject? I'm saying, "looser" filters bring nothing worthy in the end, nor "lower noise", nor "higher resolution". Nothing to do with IQ3 trichromatic.

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I don’t think loose filters bring anything worthy either. But less strict filters do allow more light to pass through to the sensor. That helps achieve better high ISO performance and supports smaller pixel pitches.

And you at least are on record for acknowledging that the filters were made less strict to achieve lower noise here:

"The difference is not in the sensors, but in the colour filters in front of the sensors. The previous generation of cameras had better separation in filters, close to Kodak recipe. In order to get less noise the filters became less strict, the CCD was replaced with CMOS, and noise reduction was applied to raw (not in all camera models). That all happened pretty much in one move. Switching to CMOS has no effect to colours (if NR before recording raw is done properly). But switching to more transparent colour filter arrays has certain effect. As a result of more transparent filters colours become more muted."

https://www.dpreview.com/forums/post/53762887

The IQ3 trichromatic rejects this trend towards loose color filters in favor of a much stricter, more balanced CFA. That’s entirely materiel to the color science.

Iliah Borg said:

Iliah Borg said:

I'm aligned with Phase One's published point of view.

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You are not. You said, "looser CFA's for higher resolution":

https://www.dpreview.com/forums/post/61583175

Are folks at Phase One saying IQ3 trichromatic has lower resolution and people getting it are at resolution disadvantage? Do you think Phase One marketing agree with you on that one?

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Yes, I do think Phase One would agree conceptually with me.

Since they are in the 100MP+ medium format market Phase One will never make a public argument against high resolution photography. With the IQ3 Trichromatic they are mainly interested in waging a war against color degradation.

However, they will probably agree that the bigger pixels of medium format are better suited for high resolution photography than the smaller pixels of full frame precisely because the former can tolerate stricter color filters.

Which brings us back to the conclusion.

fPrime

--
Half of my heart is a shotgun wedding to a bride with a paper ring,
And half of my heart is the part of a man who's never truly loved anything.

fPrime said:

Iliah is a software engineer

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No.

Like I said, you don't know what are you talking about.

J A C S said:

Iliah Borg said:

The discussion stops making sense, because, for example, one party is discussing some out-of-the-box colour transforms and follow marketing claims; while the other party is discussing limits of colour transforms' optimizations, including limits induced by different CFA formulations - and (sacrilege!) tend to discuss those "by the numbers".

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The discussion still makes sense as a practical matter, which is the whole point.

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Look at the subject line of your post above and tell me what data is discussed

Iliah Borg said:

J A C S said:

Iliah Borg said:

The discussion stops making sense, because, for example, one party is discussing some out-of-the-box colour transforms and follow marketing claims; while the other party is discussing limits of colour transforms' optimizations, including limits induced by different CFA formulations - and (sacrilege!) tend to discuss those "by the numbers".

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The discussion still makes sense as a practical matter, which is the whole point.

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Look at the subject line of your post above and tell me what data is discussed

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We discuss the reasoning, not the data.

fPrime said:

Iliah Borg said:

fPrime said:

Iliah Borg said:

fPrime said:

I've already given you the next challenge

Overcome the IQ3 trichromatic CFA sensor with measurement against a non-trichromatic CFA

Click to expand...

I don't see your own data to challenge it.

Click to expand...

Why should I?

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Think of what you just said. "Why should I?" Why should you what?

Only data can be challenged. No data - no challenge. You have no data, so you have no challenge.

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The challenge subject here isn't data

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So there is no challenge.

fPrime said:

The subject is entirely P1's characterization of why and how CFA's were weakened.

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I'm not discussing that, I gave my point of view around 2005, it didn't change since. I'm happy that now more people publicly acknowledge it, "looser" CFAs achieve nothing.

However the idea of using "looser CFAs" was all but abandoned, not in the least because what I was saying is true.

To refresh your memory, here is Dr. Fossum's response to you on that CFA matter https://www.dpreview.com/forums/post/60421216

fPrime said:

A less strict filter allows more light to pass through to the sensor. That helps achieve better high ISO performance and supports smaller pixel pitches.

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No, because noise returns with colour transforms. 2005 all over again, same mistake, I already answered that in my first post to you here.

fPrime said:

And you at least are on record for acknowledging that the filters were made less strict to achieve lower noise here:

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No, that's not what I said. The advantage of lower noise in raw as the result of lower colour discrimination and broader spectral response curves was the argument put forward by some design teams. Nikon D2H and Leica M8 were nice examples of the extremes that may result from such approach. But lower noise in raw doesn't mean lower noise on the final colour-corrected image That is one of the reasons why CMY and RGB were abandoned, while IR and UV filters became more discriminating.

fPrime said:

fPrime said:

fPrime said:

I'm aligned with Phase One's published point of view.

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You are not. You said, "looser CFA's for higher resolution":

https://www.dpreview.com/forums/post/61583175

Are folks at Phase One saying IQ3 trichromatic has lower resolution and people getting it are at resolution disadvantage? Do you think Phase One marketing agree with you on that one?

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Yes, I think Phase One would agree conceptually with me.

Since they are in the 100MP+ medium format market Phase One will never make a public argument

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So you maintain that IQ3 trichromatic has lower resolution, Phase One know it, and their marketing publications conceal that fact.

--
http://www.libraw.org/

Iliah Borg said:

Iliah Borg said:

A less strict filter allows more light to pass through to the sensor. That helps achieve better high ISO performance and supports smaller pixel pitches.

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No, because noise returns with colour transforms. 2005 all over again, same mistake, I already answered that in my first post to you here.

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But … DXO use the G channel only in their scores... I would not be surprised to learn that this plays a role in the design stage.

BTW, I strongly disagree with the "color separation" theory and I have said this many times. Still, the CFA matters.

Jack Hogan said:

Jack Hogan said:

fPrime wrote: ... 2. Test the IQ3 trichromatic camera against a standard camera with a set of subjects that typically invoke metameric failure and show that in reality there's no difference in the color performance between either.

Click to expand...

If there is a difference in the CFAs, as is implied by your thought experiment, then it's guaranteed that there will be differences in the color performance of the cameras. The question is, which will produce the better color? And once we define the context and what better color means we might have a quantitative answer, for that particular setup.

Jack

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Which will give the more accurate colour will depend on the spectrum of the test colour. One colour, for instance, might have a peak near the dominant wavelength of one of the CFA filters, another might have a peak that lies between the dominant wavelengths of two filters.

One colour may have a spectrum that slopes gently upward toward the red end, with a couple of bumps on the way. Another may have a sharp cutoff.

So "better" for one colour on one sensor can be "worse" for another colour on the same sensor.

D Cox said:

Jack Hogan said:

D Cox said:

fPrime wrote: ... 2. Test the IQ3 trichromatic camera against a standard camera with a set of subjects that typically invoke metameric failure and show that in reality there's no difference in the color performance between either.

Click to expand...

If there is a difference in the CFAs, as is implied by your thought experiment, then it's guaranteed that there will be differences in the color performance of the cameras. The question is, which will produce the better color? And once we define the context and what better color means we might have a quantitative answer, for that particular setup.

Jack

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Which will give the more accurate colour will depend on the spectrum of the test colour. One colour, for instance, might have a peak near the dominant wavelength of one of the CFA filters, another might have a peak that lies between the dominant wavelengths of two filters.

One colour may have a spectrum that slopes gently upward toward the red end, with a couple of bumps on the way. Another may have a sharp cutoff.

So "better" for one colour on one sensor can be "worse" for another colour on the same sensor.

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Actually what you are describing is worse for both colors. I suspect that one of the popular brands does this but I have no enough data to back it up.

J A C S said:

D Cox said:

Jack Hogan said:

J A C S said:

fPrime wrote: ... 2. Test the IQ3 trichromatic camera against a standard camera with a set of subjects that typically invoke metameric failure and show that in reality there's no difference in the color performance between either.

Click to expand...

If there is a difference in the CFAs, as is implied by your thought experiment, then it's guaranteed that there will be differences in the color performance of the cameras. The question is, which will produce the better color? And once we define the context and what better color means we might have a quantitative answer, for that particular setup.

Jack

Click to expand...

Which will give the more accurate colour will depend on the spectrum of the test colour. One colour, for instance, might have a peak near the dominant wavelength of one of the CFA filters, another might have a peak that lies between the dominant wavelengths of two filters.

One colour may have a spectrum that slopes gently upward toward the red end, with a couple of bumps on the way. Another may have a sharp cutoff.

So "better" for one colour on one sensor can be "worse" for another colour on the same sensor.

Click to expand...

Actually what you are describing is worse for both colors. I suspect that one of the popular brands does this but I have no enough data to back it up.

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Is it Sony cutting off greens leading to unnaturally rendered foliage, by chance?

The evidence of empirical observation is enough IMHO.

fPrime

... lower noise in raw doesn't mean lower noise on the final colour-corrected image That is one of the reasons why CMY and RGB (sorry for the typo) RGBW were abandoned, while IR and UV filters became more discriminating.