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Author Topic: Phase One Trichromatic In Depth Article with Raw Files  (Read 34220 times)

Jack Hogan

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Re: Phase One Trichromatic vs Standard Back Matrices
« Reply #120 on: January 04, 2018, 04:57:18 am »

Hi All, thanks for your comments.  Just to be clear, my renditions are entirely linear until sRGB gamma is applied: other than the linear color conversion there is no additional processing whatsoever, not even a default tone curve*, which - depending on your video/monitor setup - may be the reason for what appears as veiling.  I also did not check for clipping as my post was really about the matrices: the images were displayed in sRGB just to show that they did what they were supposed to do and produced plausible colors.

Perhaps if there is some interest I could repeat the exercise adding a tone curve and ending up in a better color space like Adobe RGB to check more meaningful visuals and clipping there.  It will have to wait for a bit though.

Jack

* See steps 1->7 here, with color step 6 = just the linear compromise matrix transform.
« Last Edit: January 04, 2018, 05:30:34 am by Jack Hogan »
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jduncan

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Re: Hi - lot of questionable info in that article
« Reply #121 on: January 04, 2018, 07:42:51 am »

Hi,

Doug's posting is not a scientific article but it does contain some alternate facts.

Doug shows a spectral plot of traditional CFA filters:


But, traditional filters look like this:


Or this:


Or this:


So Doug illustrates traditional CFA designs with fake info. There is a sensor that has some characteristics similar to the traditional CFA illustration in Doug's presentation and that is the human vision, corresponding to curve A, below:


The reason such curves are not used in digital cameras is that it would cause excessive levels of noise.

Regarding UV-filtering and IR filtering, that is really a job for the cover glass, that has an IR-filter. Optical glass doesn't transmit much in UV anyway. If UV/IR is an issue, it is not about a new design, it is about Phase One designing an underperforming cover glass on the older models.

The colour differences Doug demonstrate are well within the capabilities of properly designed camera profiles. The effects shown can possibly achieved just buying a proper test target and use Lumariver's Profile Designer.

So, my impression is that it is a marketing hyperbole. The curves that Doug shows are patently fake. If the article starts with fake facts, why would be believe the rest?

To Dougs's defense, I would assume that he just uses info he got from Phase One, but I don't think he should have use it as to much of the info is fake and it should be obvious to anyone doing colour stuff.

Best regards
Erik

This looks like a shocking result,  I did notice that P1 was returning pure market-speech when they introduced the new tool.
I stopped paying attention.  I wanted to know "what they actually did". Now I see that we have "data" but it appears to be compromised.

Thanks for sharing.

Best regards,
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Doug Peterson

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Re: Hi - lot of questionable info in that article
« Reply #122 on: January 04, 2018, 09:22:39 am »

Now I see that we have "data" but it appears to be compromised.

As I've explained before...

My aim was to explore, specifically to the non-scientific/academic community, what problems P1 was intending to solve, what general methodology they used, and what our (DT's) real-world testing showed about whether they were successful.

I started the article by explaining it would not contain scientific spectral charts, and that the charts I showed were illustrative and not to be taken literally. Quote "This will include illustrations of spectral transmission that are meant as a learning aid; these are crudely drawn and exaggerate differences to make them easier to consume, and should not be taken literally..."

Erik then proceeded to take the charts literally and judge them as if they were scientific spectral charts. Unsurprisingly he found them lacking.

It's like I posted the below explanation of precision vs accuracy for non statisticians and got the feedback that "the size of the holes were not representative of the hole of any bow and arrow, and the dispersion pattern is not reflective of a standard bowsman; here look at these forensic analysis".



There is only so much I can do. Fortunately in the real world, away from the internet forums, I've had very consistently positive feedback. By this I mean that people who read the article and then rented/tried/purchased the Trichromatic said it accurately reflected in advance the experience their own testing later provided.

Want lab measurements of the Trichromatic vs standard back? We're glad to arrange use of both for you to do so and share the results however you want.

Don't like the word-content of my article? I take no personal offense; download the raws we made available and make your own comparisons, or come play with a Trichromatic and make up your own mind.

Want a layman's explanation of why, how, and to what level of success the Trichromatic aimed to improve the color available to photographers? Then I (in my biased opinion) think my article did a decent job of that.
« Last Edit: January 04, 2018, 09:40:12 am by Doug Peterson »
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digitaldog

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Re: Hi - lot of questionable info in that article
« Reply #123 on: January 04, 2018, 10:31:26 am »

This looks like a shocking result,  I did notice that P1 was returning pure market-speech when they introduced the new tool.
I stopped paying attention.  I wanted to know "what they actually did". Now I see that we have "data" but it appears to be compromised.

There are two kinds of statistics, the kind you look up, and the kind you make up. -Rex Stout

There are lies, damned lies, and statistics.-Mark Twain


They worked for marketing departments.  :o
Be excellent if Iliah Borg showed up to provide his expert input. And while I hate to discuss the cesspool of forums on DPR, their Science and Technology area has some interesting discussions about this sensor void of much of the cess <g>.
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Jack Hogan

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Re: Phase One Trichromatic vs Standard Back Matrices
« Reply #124 on: January 04, 2018, 12:25:19 pm »

... ending up in a better color space like Adobe RGB to check more meaningful visuals and clipping there.

Here they are in their full Adobe RGB glory.  Keep in mind that now most browsers will display their colors incorrectly and to view them properly you now need to download them, open them with a fully color managed app and view them on a wide gamut display.  Interestingly, under this unusual light, much of the citrus fruit is out of gamut in both backs' captures, with the TC fairing a touch better (the big blue out of gamut ball is the orange):



The files are attached in Jpeg high.  Again all that was done to both of them is white balance, a little EC to match brightness, color transform by dedicated compromise matrix to Adobe RGB and downsized with PS bicubic.  Nothing else.  I can't tell anything from them because I am doing this on a laptop with a typically indecent screen.   Edit: updated the files, they are now brightness-matched on the third neutral patch from the right.

Jack
« Last Edit: January 07, 2018, 11:47:58 am by Jack Hogan »
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DiamondsDr

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #125 on: January 08, 2018, 11:28:02 pm »

...without going deep about ir and uv filters, while I calibrate and custom profile very often I have to visually adjust certain “colors” manually while in phocus or acr, if I was using p1 I believe would be the same story, it primarily happens with gems(they have many different properties as well) most often it’s yellow...

32BT

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #126 on: January 10, 2018, 03:19:52 am »

Okay, I think I figured it out. Attached are the two icc profiles. They are preliminary results because I haven't created visual confirmation yet, but after thinking about it, it could well be the point:

TC = less colorspace = more colordepth

Huh? Less colorspace?

Yes, by placing the green and blue primaries closer to the actual visible colorspectrum, the TC colorspace is smaller than the IQ space, but it then uses more of the bitdepth for actual visible colors. Or differently: The TC channels will saturate more quickly than the IQ channels for the same colors, thus utilising more bits for the same representation.

Attached are the profiles, plus a comparison. You can see the IQ on the left with the primaries literally "off-the-chart". This is quite normal for most camera profiles I've seen. The TC on the right however shows the green and blue primary much closer to the actual visible spectrum.
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Doug Peterson

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #127 on: January 10, 2018, 06:22:17 am »

...without going deep about ir and uv filters, while I calibrate and custom profile very often I have to visually adjust certain “colors” manually while in phocus or acr, if I was using p1 I believe would be the same story, it primarily happens with gems(they have many different properties as well) most often it’s yellow...

We’ve worked with a few shooters who specifically shoot gems, and have a system installed at the GIA (the Gemology Institute of America).

A trichromatic won’t suddenly solve all your problems or make you feel young again, but I think you would be surprised at the reduction in frequency with which you had to make such manual color corrections. The Focus Stacking tool built into the XF can also be very helpful for such work and the tethering toolset in C1 (eg overlay, color editor, Focus mask, compare variant, diffraction correction) is top notch for tiny colorful subjects. Your local P1 dealer can help you set up a test; if you’re in the US we’d be glad to.

32BT

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #128 on: January 10, 2018, 05:47:59 pm »

Okay, I think I figured it out. Attached are the two icc profiles. They are preliminary results because I haven't created visual confirmation yet, but after thinking about it, it could well be the point:

TC = less colorspace = more colordepth

Visually confirmed.

« Last Edit: January 10, 2018, 05:51:10 pm by opgr »
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DiamondsDr

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #129 on: January 10, 2018, 10:57:36 pm »

We’ve worked with a few shooters who specifically shoot gems, and have a system installed at the GIA (the Gemology Institute of America).

A trichromatic won’t suddenly solve all your problems or make you feel young again, but I think you would be surprised at the reduction in frequency with which you had to make such manual color corrections. The Focus Stacking tool built into the XF can also be very helpful for such work and the tethering toolset in C1 (eg overlay, color editor, Focus mask, compare variant, diffraction correction) is top notch for tiny colorful subjects. Your local P1 dealer can help you set up a test; if you’re in the US we’d be glad to.

Hi Doug, as for GIA they can have any system or multiple systems they want, it’s a big organization with wide spectrum of work(I’ve studied there) and I’m in the industry for a long time...obviously I was using different cameras systems over the years with ability to deliver results for different media’s. I wasn’t complaining about manual adjustment’s it’s a part of the process as I mentioned above due to the properties of the stones so obviously there is no prefect camera..and while I love “new” technology’s and always looking to make “prefect “ results it has to make economic sense as well...

Jack Hogan

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #130 on: January 11, 2018, 12:00:58 pm »

Okay, I think I figured it out. Attached are the two icc profiles. They are preliminary results because I haven't created visual confirmation yet, but after thinking about it, it could well be the point:

TC = less colorspace = more colordepth

Interesting Oscar, kind of makes sense in a ProPhoto vs Adobe RGB working color space sort of way.  I am not familiar with the primaries shown, do you know how they are computed?
« Last Edit: January 11, 2018, 12:23:19 pm by Jack Hogan »
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Jack Hogan

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #131 on: January 11, 2018, 12:02:41 pm »

Should anyone be interested I have put a little more detail online about my thinking and analysis of David's captures with the two backs (geek alert):

http://www.strollswithmydog.com/phase-one-iq3-100mp-trichromatic-linear-color-i/

Jack
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dchew

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #132 on: January 11, 2018, 01:32:10 pm »

Should anyone be interested I have put a little more detail online about my thinking and analysis of David's captures with the two backs (geek alert):

http://www.strollswithmydog.com/phase-one-iq3-100mp-trichromatic-linear-color-i/

Jack

Fantastic job Jack. Heck, even I could follow it!

As I mentioned in a message to Jack, I apologize for shooting them at different ISOs, but I wanted to compare them as I would typically use them. I was less interested in a scientific comparison. Although now I am intrigued by Jack's posts. Someday I should do this again.

Although I took several images from each bracketing by 1/3 stops, no exposures were identical between the two backs. Perhaps if I would have set the backs to 1/2 stop increments instead of my normal 1/3 stop increments...

Regardless, fascinating stuff Jack, and thank you for the analysis.

Dave
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32BT

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #133 on: January 12, 2018, 02:06:05 am »

Interesting Oscar, kind of makes sense in a ProPhoto vs Adobe RGB working color space sort of way.  I am not familiar with the primaries shown, do you know how they are computed?

Yes, similarly to your forward-matrix description, but when you have the XYZ coordinates you convert to Yxy.

(Regarding your description for forward matrix conversion it may be of interest that technically there are only 6 unknowns. One coordinate of each primary is given by subtraction from white. The xy coordinates of the primaries are therefore "sufficient" to describe the space.)
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Jack Hogan

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #134 on: January 12, 2018, 02:18:14 am »

Thank you David, it was fun.  And thank you again for sharing the captures.

Jack
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Jack Hogan

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #135 on: January 12, 2018, 03:05:01 am »

Yes, similarly to your forward-matrix description, but when you have the XYZ coordinates you convert to Yxy.

Ah, ok.  So what are the three raw coordinates that are converted to Yxy: (1,0,0), (0,1,0) and (0,0,1)?

(Regarding your description for forward matrix conversion it may be of interest that technically there are only 6 unknowns. One coordinate of each primary is given by subtraction from white. The xy coordinates of the primaries are therefore "sufficient" to describe the space.)

Thanks for your comment Oscar, you are correct.  Decreasing the number of unknowns from 9 to 6 would be great but I normally prefer to let all 9 fluctuate in the process of finding the optimum compromise matrix (as you know some people use 12, adding a bias term to each channel).  I then check the final resulting white point to make sure it is in the ballpark of the illuminant, and it normally is pretty close (see my article on determining the forward matrix for a better example).  In this case it is a little bit off for the reasons mentioned I believe (and the fact that we do not have actual measured reflectances).  You can see the white point in the line 'sum of XYZ rows' in the printouts: 6591K vs 6503K for D65.  How accurately do we know the CCT of the actual illuminant?



The advantage is that I have more degrees of freedom in achieving more 'accurate' tones overall, perhaps at the expense of the neutrals.  I also get to see whether there is something off anywhere in the setup by using the neutral tones as a known test set :)  The disadvantage is that the full-trip to the desired colorimetric color space may not yield a perfectly exact white point.  The final check is in the 'sum of RGB rows' line in the printout which should be (1,1,1) but is instead (0.99,1.01,1.00) for Adobe RGB, I'll give it a pass.  FYI a* and b* are (0,0) in Photoshop for all but the first neutral to the left, and we know that's off on its own.

But your point is very well taken, thanks again.

Jack



« Last Edit: January 12, 2018, 03:35:20 am by Jack Hogan »
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douglevy

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #136 on: January 12, 2018, 10:25:57 am »

Holy science class batman! I'm a geek, but whoa...

Peter McLennan

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #137 on: January 12, 2018, 11:44:17 am »

No kidding.
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32BT

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #138 on: January 12, 2018, 06:41:00 pm »

Ah, ok.  So what are the three raw coordinates that are converted to Yxy: (1,0,0), (0,1,0) and (0,0,1)?

Yes.

... but I normally prefer to let all 9 fluctuate in the process of finding the optimum compromise matrix (as you know some people use 12, adding a bias term to each channel).  I then check the final resulting white point to make sure it is in the ballpark of the illuminant, and it normally is pretty close

That is indeed useful to check if the underlying algo's operate as desired, though from experience I have found that it is extremely sensitive to how evenly the lighting of the target was (that includes the target itself being bend or deformed) and the incidence of the light which is a problem particularly visible for the caucasian patch. The 3 additional degrees of freedom primarily act as multipliers for the whitebalance, but we already took that step.

So, to eliminate as many variables as possible, it is probably best practice to fix the whitepoint, and – to avoid as many cans of worms as possible – I personally prefer to use illuminant E. The latter simplifies spectral data conversions for the colorpatches. No need to know the spectral data of the original illuminant, or obfuscate the results with daylight spectra.

The issue that currently has me wondering is this: what explains the difference in the caucasian patch between the IQ and the TC. In both your conversion and mine the patch is significantly more red. This could perhaps be a combination of the patch heating up between the shots and different (IR) filtration on the sensor. I would very much like to see some comparative portraits with both camera's.


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ErikKaffehr

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #139 on: January 13, 2018, 12:32:01 am »

I second all that! Thanks for sharing!

Best regards
Erik


Fantastic job Jack. Heck, even I could follow it!

As I mentioned in a message to Jack, I apologize for shooting them at different ISOs, but I wanted to compare them as I would typically use them. I was less interested in a scientific comparison. Although now I am intrigued by Jack's posts. Someday I should do this again.

Although I took several images from each bracketing by 1/3 stops, no exposures were identical between the two backs. Perhaps if I would have set the backs to 1/2 stop increments instead of my normal 1/3 stop increments...

Regardless, fascinating stuff Jack, and thank you for the analysis.

Dave
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