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Author Topic: Phase One Trichromatic In Depth Article with Raw Files  (Read 10401 times)

ErikKaffehr

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Re: Hi - lot of questionable info in that article
« Reply #20 on: October 21, 2017, 10:58:28 AM »

Hi Doug,

You don't happen to have real world CFA plots from the Thrichromatic and say the IQ3-100MP, showing the difference you get for another 40 k$US?

The Madmax plots are about cameras with the IR-filter removed.

Best regards
Erik


Traditional CFAs (as the ones you posted show) often:
- Leak red (and sometimes green) in the 400-500nm near-UV range (look at your own charts). It's not a lot and our graph exaggerates it to make it clear.
- Err a bit on the side of too much overlap, prioritizing ISO over better color.
- Leak green and blue in the 600-700 near-IR range. Again, our graphs exaggerate it to increase clarity.

Note that the illustration of the spectrum we used is not of any one specific traditional CFA camera. Not every traditional CFA has every issue it illustrates.

Here from MaxMax measurements for three dSLRs without IR-cut filter in place, compared to the illustration we provided:





Note that I've used the words "near UV" and "near IR" a couple times here and in the article to refer to the outer most range within the visible spectrum.  In more scientific terms this would normally refer to the area immediately below and above visible light. That's probably a faux pas on my part. But again, scientists are not the target for this article. And this thread illustrates why: scientists tend to get caught a bit in the nitty-gritty scientific details, which is great for research, but a bit stuttering for normal photographers wanting information to help make purchasing decisions.
« Last Edit: October 21, 2017, 11:04:26 AM by ErikKaffehr »
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Doug Peterson

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Re: Hi - lot of questionable info in that article
« Reply #21 on: October 21, 2017, 11:07:42 AM »

You don't happen to have real world CFA plots from the Thrichromatic and say the IQ3-100MP, showing the difference you get?

Erik, I addressed this in the intro to the article. You seem to be taking an unusually insulting, mean spirited and derisive tone in this thread, which isn't like you. Is everything okay?

Do you have an IQ3 100mp you are considering upgrading? If so I'd suggest working with your local dealer to arrange whatever testing you would consider useful. We (DT) are glad to arrange that for anyone in the US.

Even if the intellectual property of those plots were available without an NDA my strong recommendation we be against buying a camera based on a chart. Your own hands on testing is always preferable; short of that, relevant raw files are a reasonable substitute if they match up to your type of photography.
« Last Edit: October 21, 2017, 11:12:33 AM by Doug Peterson »
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Doug Peterson

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #22 on: October 21, 2017, 11:22:18 AM »

I'll be back Monday to answer any other questions or feedback. I'm off to a Rangers game with my wife.
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sandymc

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #23 on: October 21, 2017, 11:25:12 AM »

The advantage is the color the camera produces. For that raw files, comparative tests, and the availablity of the camera for testing by prospective buyers are all far more useful than charts. We provide all of those.

Well, good luck with that. At the price, I'd think buyers would want more. But that's me.

Sandy
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Jim Kasson

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Re: Hi - lot of questionable info in that article
« Reply #24 on: October 21, 2017, 11:40:08 AM »

Traditional CFAs (as the ones you posted show) often:
- Leak red (and sometimes green) in the 400-500nm near-UV range (look at your own charts). It's not a lot and our graph exaggerates it to make it clear.
- Err a bit on the side of too much overlap, prioritizing ISO over better color.
- Leak green and blue in the 600-700 near-IR range. Again, our graphs exaggerate it to increase clarity.


What you call near-UV leaking in the red filter is essential if the sensor is to recognize spectral violet.

By the way, what's the SMI of the new camera?

Jim

ErikKaffehr

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Re: Hi - lot of questionable info in that article
« Reply #25 on: October 21, 2017, 04:22:17 PM »

Hi Doug,

I am a bit irritated because you give fake information. No camera maker has CFA designs you describe! Would you mention any camera vendor by name, you would have lawyers knocking on your door.

I don't think competitors are that impressed by NDAs, by the way. The MFD industry must be in deep trouble if they cannot afford a monochromator and a spectrometer. Alexey Danilchenko and Iliah Borg published specs for an open source spectrometer, BTW.

Just to say, CFA pigments are mostly made by Fujifilm and the sensors are built at Sony. You don't think Sony or Fujifilm don't know what filters their customers use?

The information you share is fake, and that is bad! It is quite possible that the new Phase back has exceptional colour, but please don't explain it using with some fake curves representing artist vision.

Just to say, if someone confronts me MTF data for Zony lenses I always ask, are those curves coming from the optical department or designed by the advertising department. I sort of insist of presented data to be real. I don't appreciate alternate facts or fake data.

So, yes, I am a bit upset.

Would you be interested in relation between CFA design and colour rendition, this thread may give some insights:
https://www.dpreview.com/forums/post/60254043

There are some heavy hitters posting on that thread.

Best regards
Erik



Erik, I addressed this in the intro to the article. You seem to be taking an unusually insulting, mean spirited and derisive tone in this thread, which isn't like you. Is everything okay?

Do you have an IQ3 100mp you are considering upgrading? If so I'd suggest working with your local dealer to arrange whatever testing you would consider useful. We (DT) are glad to arrange that for anyone in the US.

Even if the intellectual property of those plots were available without an NDA my strong recommendation we be against buying a camera based on a chart. Your own hands on testing is always preferable; short of that, relevant raw files are a reasonable substitute if they match up to your type of photography.
« Last Edit: October 21, 2017, 04:29:09 PM by ErikKaffehr »
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BobShaw

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #26 on: October 21, 2017, 07:33:27 PM »

Please don't change the name of the subject
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BernardLanguillier

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #27 on: October 21, 2017, 08:18:08 PM »

Important progress in colors are possible as demonstrated by the D850, so I am for one willing to believe that P1 may have progressed significantly as well.

Nikon hardly mentions their progress in their marketing material, P1 makes it the single highlight of a new product... these are slight cultural differences. ;)

Cheers,
Bernard
« Last Edit: October 22, 2017, 08:08:20 AM by BernardLanguillier »
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Garry Sarre

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Re: Hi - lot of questionable info in that article
« Reply #28 on: October 22, 2017, 10:21:50 AM »

Hi Doug,

I am a bit irritated because you give fake information. No camera maker has CFA designs you describe! Would you mention any camera vendor by name, you would have lawyers knocking on your door.

Best regards
Erik

Erik.

There's a difference between 'fake' and simplified information. Fake implies 'deliberately misleading'. Doug's article was targeted to an audience with a certain level of technical understanding and his simplified graphs were easy to get the gist of.

In my opinion, you have been a bit insulting towards Doug, who has responded graciously with his enquiry as to your wellbeing.

A well written article by the way Doug.

Garry
« Last Edit: October 22, 2017, 08:16:13 PM by Garry Sarre »
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ErikKaffehr

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Re: Hi - lot of questionable info in that article
« Reply #29 on: October 22, 2017, 12:22:29 PM »

Hi Garry,

Your comment is much appreciated.

Let me explain my standpoint a bit, look at some real data from traditional sensors:



These are probably from a DALSA sensor (o-marks), Canon 5dIII (dashed) and a Kodak sensor straight.

Now, Doug shows these curves as typical of traditional CFA designs:


The curves Doug presents as traditional approach lack scales, but we can still see some characteristics that are clearly absent in the real world data:
  • The peak in the red channel is missing in real world data.
  • Crossover between red and blue is pretty high
  • The slope of the red channels on the left is very wide
  • The green and blue curves have high values on the right side of the graph. In real world data they are zero.

So the curves shown as traditional are very dissimilar from real world curves. Would Doug say that the traditional curve was "Hasselblad", Hasselblad would certainly become very much upset. The curves also contain features not existing in real data, that actually makes them fake, they don't simplify but they do misspresent.

The left flank on the red channel is typically very steep. The right side the IR-filter sets in. It could be that Doug presented a curve without IR filter going well into the near infrared, but sensors have IR filters. Sometimes a bit to weak, like on the Nikon D200 and the Leica M8, I would recall.

Sony sensors seem to have a red channel response between between P1 (DALSA?) and H2D (Kodak?).


Canon sensors differ a bit in that crossover of blue and red are not at zero,  but the cross over is still far below Doug's illustration:



So, what about the Thrichromatic? Doug here shows a diagram that is much closer to real world traditional sensors than the traditional sensor.


Now, do you think that the image on the left is closer to traditional CFA response than the illustration at the right?

So what Doug says is that traditional sensor response is very different to reality.  Than he uses a diagram that is pretty close to traditional sensor design to say that it is better design. In engineering where I come from you are not allowed to do such things and in science definitively not.

Now, it my not be Doug's fault, he almost certainly got the illustrations from Phase One.

Later in the article, Doug states that the Thrichromatic probably does not benefit the Cultural Heritage work, as it is numerically driven field. This could indeed be the case. Quite possible that the Cultural Heritage work has better controlled lighting conditons.

Still, he indicates that some problematic colours, like Cobolt Blue may reproduce better colour. I have checked a bit on Cobolt Blue and it has an interesting reflection spectrum, intensive in blue, but lacking greens and reds but having very high intensity in IR. Could it be that Thrichromat has a steeper IR filter than older Phase One backs?


Best regards
Erik


Erik.

There's a difference between 'fake' and simplified information. Fake implies 'deliberately misleading'. Doug's article was targeted to an audience with a certain level of technical understanding and his simplified graphs were easy to get the gist of.

In my opinion, you have been a bit of an insulting dick towards Doug, who has responded graciously with his enquiry as to your wellbeing.

A well written article by the way Doug.

Garry
« Last Edit: October 22, 2017, 12:48:20 PM by ErikKaffehr »
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chrismuc

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #30 on: October 22, 2017, 04:33:17 PM »

Erik might be a bit upset in his tone but I think he is right.
Doug's spectral sensitivity graph for the Trichromatic looks basically exactly like Eric's last graph for a normal Canon 5DII/ Sony NEX/ Nikon D2X, so what's so special about Phase' new back? And btw, the artistic graphs from Phase' website illustrating a complete absence of cross-channel sensitivity were wrong and misleading anyway ...
I believe that the Tri might have a very slight advantage in color reproduction (Doug's samples show this better than Phase' samples on their website) compared to the normal IQ3100 but still seams mainly a marketing hype to me.
I consider to attend a Trip demo this week in Munich, so let's see what I can report from there.
(I hope Phase sends also an engineer/physicist not only marketing people to be able to provide some profound information.)
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Garry Sarre

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #31 on: October 22, 2017, 08:23:36 PM »

Erik.

Thanks for explaining where you are coming from and showing your more gracious side.

I think the proof will be in the pudding as I don't think Phase would put all this energy and money into something that wasn't a fairly significant move forward.
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dchew

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #32 on: October 22, 2017, 09:24:13 PM »

For what it's worth...

  • Looking at the raw files that have been offered, as well as the comparison "slider" images, the color difference is subtle.
  • Right or wrong, products from P1 and Hasselblad have been regarded as having good color.

Maybe, just maybe, the changes to the spectral sensitivity curves are also quite subtle. Maybe it is also time we brought out into the open the elephant in the room: Lately, Hasselblad has been getting a lot of kudos for their color. Phase One made some hardware "tweaks" to improve their color response, and is marketing the hell out of it. Whether those "tweaks" were significant or not depends on your disposition and what's important to you. And this is where I give Doug a break. DT, CI, Dodd, and all the other dealers I've had the pleasure doing business with say the same thing: Try it before you buy it. If you prefer the results, then buy if you want. If you do not prefer the results, or do not think the results are worth the price, don't buy it.

Erik is right in his analysis, but in my opinion is being harsh, as if P1 and its dealer network are advertising sugar-soaked cereal to unsuspecting 6 year-olds on TV. That is not the context of how this stuff is sold.

Dave
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ErikKaffehr

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #33 on: October 23, 2017, 01:34:34 AM »

Hi Chris,

Thanks for chiming in. That I react that strongly may depend on my professional experience was mostly in reactor physics for something like 30 years. First couple of years I was involved nuclear fuel testing later into modelling nuclear reactors for simulators. In my business we never had an artistic license.

I went back to look at some of the real world curves, and the right end is clearly cut off by the IR filter.

Once upon the time I planned to write an article for OnLandscape and measured spectral reflectance on some flower parts and those had very high IR content. I would think the IR-cut off filter may have a major effect on separation of greens. The IR filter is normally not a part of the CFA, but it is a part of the cover glass.

Doug also shows a sample demonstrating that the Thrichromatic reduces chromatic aberration. That would be axial chromatic aberration.

Lloyd Chambers have found a great amount of violet fringing on some Leica lenses, but discovered that it disappeared when illumination was by LED. He figured that it could be caused by UV or IR and the lenses not being corrected for wavelengths outside visual. Lloyd has than tested with different IR and UV cut off filters and got rid of the unwanted colour.

Doug shows a sample where there is some magenta fringing on the IQ3100MP that goes away on the Trichromatic. That may indicate that IR and UV cut off are a bit tighter on the Thrichromatic.

I don't think you would do this at the pixel level, it is the job of the cover glass.

I guess I am going to get me a lime and measure the reflection spectrum. Doug writes in his article, second part, that lime shows better colour with the Trichromatic. I guess the lime surface reflection may have high IR content.

Best regards
Erik







Erik might be a bit upset in his tone but I think he is right.
Doug's spectral sensitivity graph for the Trichromatic looks basically exactly like Eric's last graph for a normal Canon 5DII/ Sony NEX/ Nikon D2X, so what's so special about Phase' new back? And btw, the artistic graphs from Phase' website illustrating a complete absence of cross-channel sensitivity were wrong and misleading anyway ...
I believe that the Tri might have a very slight advantage in color reproduction (Doug's samples show this better than Phase' samples on their website) compared to the normal IQ3100 but still seams mainly a marketing hype to me.
I consider to attend a Trip demo this week in Munich, so let's see what I can report from there.
(I hope Phase sends also an engineer/physicist not only marketing people to be able to provide some profound information.)
« Last Edit: October 23, 2017, 02:53:40 AM by ErikKaffehr »
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torger

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #34 on: October 23, 2017, 02:50:34 AM »

Haven't had time to look into this in detail, but I just want to make a quick comment.

Less overlapping filters are not new, in fact as far as I know early sensors had much less overlap than newer ones. This yields more saturated colors directly out of the sensor, and the advantage of this is that the camera profile (or manual post-processing) does not need to increase saturation further. As increasing saturation means increasing noise, this is good. Early sensor were very noisy so this design approach was sort of necessary.

However the disadvantage (if we skip the high ISO sensitivity part which is not important for MFD anyway) is that if you actually want to post-process the colors you are worse off. With less overlapping filters the profile (and your manual post-processing) cannot control the color to the same extent. The color is what it is out of camera and the camera profile is better off not trying to work against it. Let's take a saturated red color as an example. With less overlapping filters that will on the raw level have large amounts of red signal and very small amounts of green and blue. A standard sensor will have large amounts of red, but also quite significant of green and blue. This means that the camera profile will have to reduce green and blue to provide proper saturation (increasing noise) but it also means that it has better ability to differ between nuances of those reds and pull them in desired direction -- as it can look at the variations of blue and green content to differ between reds.

The camera with less overlap will have low levels of blue and green in the reds and thus if the camera profile wants to differ between nuances there's more noise in the "nuance channels" so it's better off leaving the color as much as possible as-is. Phase One claim better nuances with the new sensor, and if you don't need to modify the color that is true as the color is then more complete with less contamination directly out of the sensor.

To summarize one can say that a camera that produces more saturated colors directly on sensor is not as friendly for having it's color tuned in software. However if you like the color as-is, it's all fine and better.

I wonder what design target they have had for the colors. If it is reproduction (accurate color, good for reproduction work but can be boring for other things), or a pleasing "Phase One look" which you may or may not like. My guess is that have gone more for the look, and maybe those working with reproduction is better off using the standard sensor. Likewise, those making lots of creative color post-processing may be better off with the standard sensor.

Those that make minimal post-processing and like the out-of-camera look will probably be better off with the new, but was there really a color noise problem with the old? Or are we trading color flexibility for something that really isn't needed?
« Last Edit: October 23, 2017, 02:56:38 AM by torger »
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torger

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #35 on: October 23, 2017, 03:56:32 AM »

They do claim better ISO (with example), which is interesting. With less overlapping filter you capture less signal (=>worse ISO) but as colors are more saturated out of the sensor you don't need to push it as much (=>better ISO). My guess is that there actually is worse ISO for the really high were colors are pretty bad anyway, but they have struck a balance at reasonable ISOs where you may get better results.

There's usually a fair bit of taste involved so ISO performance in the final processed result is not so easy to judge. Personally I prefer some chroma noise if colors look more alive and real on a distance, than a cleaner but brownish-pastel-like look. So in the example shown I actually believe that the standard sensor may look better in a real image despite the extra noise, but it may be more about post-processing tuning rather than sensor performance.

Another interesting aspect is black and white conversion, which again is claimed to be improved with the new less overlapping color filters. Although it's true that you could get a less noisy result, that should only apply if you don't modify the already captured colors. If you want to pre-process colors a fair bit to achieve better black and white separation in some circumstances, there's a risk that you actually get more noise instead, according to the principle if the color is purer (more saturated) it has less signal in the other channels and is thus harder to modify. So I would proceed with caution and really test this thing if you do a lot of black and white work.
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Jim Kasson

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #36 on: October 23, 2017, 11:52:33 AM »


Less overlapping filters are not new, in fact as far as I know early sensors had much less overlap than newer ones. This yields more saturated colors directly out of the sensor, and the advantage of this is that the camera profile (or manual post-processing) does not need to increase saturation further.

This is news to me. In the work that Jack Hogan and I have done so far on the relationship of overlap and SMI, it appears that SMI suffers when there is too much and when there is too little overlap. We have not -- so far -- investigated the direction of the errors.

Are you suggesting that in the computation of the optimum compromise matrix that reducing overlap biases the errors wrt the reference values for the training set in the direction of increased chroma?

It should be possible to test that, but before I do so, I want to verify if that's what you are claiming.

Jim

sandymc

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #37 on: October 23, 2017, 02:06:52 PM »

This yields more saturated colors directly out of the sensor

Hmmm. You lost me right about there. The whole concept of a bayer sensor, at least a sensor with non-trivial overlap, having "saturation" is not, IMHO, very useful. They really don't (a) in any way that it's useful for a human to think about or (b) in any way that makes sense in a mathematical form.

Sandy
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Jim Kasson

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #38 on: October 23, 2017, 03:47:39 PM »

Hmmm. You lost me right about there. The whole concept of a bayer sensor, at least a sensor with non-trivial overlap, having "saturation" is not, IMHO, very useful. They really don't (a) in any way that it's useful for a human to think about or (b) in any way that makes sense in a mathematical form.

Agree with that, unless the sensors are Luther-Ives compliant (and then the saturation would be perfect by definition). I took the remark to discuss colors after multiplication by the compromise matrix, however.

Jim

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Re: Phase One Trichromatic In Depth Article with Raw Files
« Reply #39 on: October 23, 2017, 04:14:58 PM »

Looking at the comparison "slider" images on the DT website, the difference is so small I just don't get it.  Personally I don't care that much about "accurate" color since I tweak them anyway in post.

Now here we have the implication your old back is no good so you need to upgrade. Not a chance.
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