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ErikKaffehr

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A few questions about camera profiles
« on: February 13, 2014, 12:45:44 am »

Hi,

A few photographers have recently tested profiles made for the IQ-250 with other sensors like the D800 and Canon and seems to have achieved more satisfactory results.

I was for some time thinking about camera profiles, and I have a few questions:

1) How are they made? Are they using spectral sensivity data to calculate response for different illuminants?

2) Do camera profiles convert raw data in CIE X,Y,Z or into working space like Prophoto RGB? Converting to X, Y, Z makes a lot of sense to me.

3) Having a good conversion to working space (like Prophoto RGB) and having rendering profiles (or presets) seems to me a better approach than combining both into a single profile.

4) How much of this is solid math and how much black magic?

I have some very basic understanding of how things work, but I feel that there is a lot of confusion about how profiles are handled, and what they mean, in raw conversion.

Would be nice the hear from those who know, like some barks from the forum terrier bit bull or the digital dog. Comments from the man in chains would also be most interesting.

Best regards
Erik

« Last Edit: February 13, 2014, 01:38:27 am by ErikKaffehr »
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Schewe

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Re: A few questions about camera profiles
« Reply #1 on: February 13, 2014, 01:16:43 am »

Would be nice the hear from those who know, like some barks from the forum terrier or the digital dog. Comments from the man in chains would also be most interesting.

I'll let Eric decide how much to say...so, are you calling me a terrier? A TERRIER? If you were referring to me, I would much rather be compared to a bit bull, just saying :~)

So, your question is pretty wide open. Are you referring to DNG Profiles or ICC camera profiles. There's a big difference...

If you are referring to DNG Profiles, at Adobe, Eric or Thomas (or maybe a new guy) use a pretty exotic piece of hardware to to generate the Adobe Standard DNG profiles. Exactly how they do it may be proprietary...but they are profiled at D65 and Standard Illuminate A (2850ºK, I think). In ACR/LR, the resulting dual illuminate profile is tweened between the two illuminates and extrapolated when above or below the K range.

As far as I know, the camera color is interpreted into CIE XYZ and the internal working space is linear gamma, ProPhoto RGB. The transform for the final output profile is also, I think, done in CIE XYZ. In the processing pipeline, a lot of "magic" occurs...some processes are only on luminance (like sharpening) other processes are in HSB (it says HSL but it's a misnomer, I'm pretty sure Eric told me it's actually working in HSB which is a tiny bit different than HSL).

Not sure what you are asking in Q3...wanna try again?

In terms of the math, well, Thomas Knoll figured it all out. Thomas knows the math really well (he invented some of it) but the thing about Thomas is that's he's a master of "magic numbers", which means he' knows what the results are that he wants and if the math doesn't quite get it, he's perfectly happy and willing to tweak the numbers the way he wants.

I watched Thomas reverse engineer the raw file from one of my cameras (an early Canon D30) before ACR was actually released...it was interesting but kinda like watch corn grow...it got boring pretty quick but Thomas was fascinated. Back then he shot two raw shots with an X-Rite ColorChecker DC in a SpectraView Jr light booth under D65 and Standard Illuminate A. The process has evolved a lot since then :~)

BTW, you can learn a lot about DNG Profiles if you read the full DNG Spec.

If you are asking about camera ICC profiles, sorry, I don't think they are particularly useful...(even though Capture One uses them).
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ErikKaffehr

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Re: A few questions about camera profiles
« Reply #2 on: February 13, 2014, 01:43:52 am »

Hi,

Terrier issue fixed…

Regarding Q3, there may be different profiles. My questions is really if those profiles are applied before or after conversion to XYZ. The question may make little sense, but may give cause to some interesting discussion.

Thanks a lot for thoughtful response! And I hope you excuse me for the small joke.

Best regards
Erik


I'll let Eric decide how much to say...so, are you calling me a terrier? A TERRIER? If you were referring to me, I would much rather be compared to a bit bull, just saying :~)

So, your question is pretty wide open. Are you referring to DNG Profiles or ICC camera profiles. There's a big difference...

If you are referring to DNG Profiles, at Adobe, Eric or Thomas (or maybe a new guy) use a pretty exotic piece of hardware to to generate the Adobe Standard DNG profiles. Exactly how they do it may be proprietary...but they are profiled at D65 and Standard Illuminate A (2850ºK, I think). In ACR/LR, the resulting dual illuminate profile is tweened between the two illuminates and extrapolated when above or below the K range.

As far as I know, the camera color is interpreted into CIE XYZ and the internal working space is linear gamma, ProPhoto RGB. The transform for the final output profile is also, I think, done in CIE XYZ. In the processing pipeline, a lot of "magic" occurs...some processes are only on luminance (like sharpening) other processes are in HSB (it says HSL but it's a misnomer, I'm pretty sure Eric told me it's actually working in HSB which is a tiny bit different than HSL).

Not sure what you are asking in Q3...wanna try again?

In terms of the math, well, Thomas Knoll figured it all out. Thomas knows the math really well (he invented some of it) but the thing about Thomas is that's he's a master of "magic numbers", which means he' knows what the results are that he wants and if the math doesn't quite get it, he's perfectly happy and willing to tweak the numbers the way he wants.

I watched Thomas reverse engineer the raw file from one of my cameras (an early Canon D30) before ACR was actually released...it was interesting but kinda like watch corn grow...it got boring pretty quick but Thomas was fascinated. Back then he shot two raw shots with an X-Rite ColorChecker DC in a SpectraView Jr light booth under D65 and Standard Illuminate A. The process has evolved a lot since then :~)

BTW, you can learn a lot about DNG Profiles if you read the full DNG Spec.

If you are asking about camera ICC profiles, sorry, I don't think they are particularly useful...(even though Capture One uses them).
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Schewe

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Re: A few questions about camera profiles
« Reply #3 on: February 13, 2014, 01:53:51 am »

Regarding Q3, there may be different profiles. My questions is really if those profiles are applied before or after conversion to XYZ. The question may make little sense, but may give cause to some interesting discussion.

Well, if you are referring to DNG profiles, well, it's complicated...

By default, when you open an image in ACR/LR, the metadata is read from the camera and ACR/LR picks a white balance starting point based on the metadata. If the WB is between the dual illuminates, ACR/LR interpolates between the dual illuminates. As you adjust the WB, the modifications are previewed. So, the way the DNG profile works is to first convert from camera color and then into the working space by way of the DNG profiles and the white balance selected and then transform the preview into the display color space (again using, I think, CIE XYZ). A lot of under the hood stuff happens up to the point where you process...it's pretty messy under that hood, Eric tried to explain some of it to me, but it made my eyes glaze over :~)

The final images after running through the pipeline is then transformed to the output profile selected. In ACR 8.x in Photoshop CC, that output profile can be any ICC profile including RGB, Lab, CMYK or grayscale. In LR only RGB color profiles are supported.
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Vladimirovich

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Re: A few questions about camera profiles
« Reply #4 on: February 13, 2014, 02:30:50 am »

Well, if you are referring to DNG profiles, well, it's complicated...
it is described in http://www.adobe.com/content/dam/Adobe/en/products/photoshop/pdfs/dng_spec_1.4.0.0.pdf and for people able to read the code also DNG SDK code is a book to read...
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Vladimirovich

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Re: A few questions about camera profiles
« Reply #5 on: February 13, 2014, 02:40:41 am »

http://forums.adobe.com/message/3183090#3183090

http://forums.adobe.com/message/3958507#3958507

just scan posts from Eric Chan and you shall see a lot of comments about how Adobe software works (DNG profiles)
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Bart_van_der_Wolf

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Re: A few questions about camera profiles
« Reply #6 on: February 13, 2014, 04:17:32 am »

Hi,

A few photographers have recently tested profiles made for the IQ-250 with other sensors like the D800 and Canon and seems to have achieved more satisfactory results.

I was for some time thinking about camera profiles, and I have a few questions:

1) How are they made? Are they using spectral sensivity data to calculate response for different illuminants?

Hi Erik,

Since you are referring to the new PhaseOne IQ250 ICC profile, as used in CaptureOne, I think the DNG profile info you already got is not going to answer your questions fully. Do note that the DNG profiles used in LR/ACR are something different from ICC profiles.

Although they may use a different starting point (e.g. a monochromator), I think PhaseOne starts out by shooting an image (more likely a series at different exposure levels) of a Digital ColorChecker SG chart, which uses 140 color patches instead of the 24 of a common, or Passport, Colorchecker. They could also use an IT8 standard chart, e.g. one from Wolfgang Faust (http://www.targets.coloraid.de/) which are usually of high quality.

Shooting such a target requires a very neutral shooting environment/studio/lab, because we do not want any ambient light influences/reflections to be mixed in with the main illuminant's spectral output. Also surface reflections from the illuminants must be minimized as much as possible (as in a good repro setup), since that will reduce the saturation of the patches and produce over-saturated/compensated results, and light-fall off must be miniimized.

The chart comes with an accompanying reference data set (usually as a file that comes with the profiling software, or one can read the actual chart colors with a spectrophotometer), and the profiling software will then compare the camera's recorded colors after White Balancing and demosaicing with the target colors, adjust the input and create look-up tables that convert the Raw demosaiced data into the desired/expected input data. That calibrated data can then be converted with a Profile to the Working space and finally to the Output colorspace. Such profiles are Scene referred profiles, and as such well suited for transformations through the imaging chain when the other components are also well profiled. The only drawback is that they are most accurate for the exact same lighting conditions as existed during shooting of the target. The more the actual scene lighting conditions differ, the more inaccuracies can develop (but then we usually do not want accurate colors but rather pleasing colors anyway, and our eyes do not respond exactly the same as RGB trichromatic sensors either).

The software that creates the (calibration) lookup tables and ICC profile, can influence/adjust several things in the creation of that profile, which will e.g. result in more (or less) contrast and saturation. But it also allows to shift the accuracy of interpolation for certain color ranges or even the response for those colors which can shift their colors, but at the same time compress or expand other colors. It is also possible to adjust the colors of the Raw demosaiced input file for the profiling software, which will then try to compensate in the opposite direction.

Quote
2) Do camera profiles convert raw data in CIE X,Y,Z or into working space like Prophoto RGB? Converting to X, Y, Z makes a lot of sense to me.

Camera profiles (ICC type) just translate from one set of coordinates to an other set of coordinates, and there are several almost lossless conversions between coordinates systems possible. XYZ or L*a*b are common device independent coordinate systems, and it is possible to convert calibrated RGB colors into and from those coordinates.

Quote
4) How much of this is solid math and how much black magic?

I think a lot of it is solid math, although the math is adjustable to allow and deal with imperfect (trichromatic) input and match with spectrally accurate data, which is already a bit of magic (some profilers produce better results than others, so it's not straightforward calculus). But the result will not be perfect, and the tweaking that will then be done could be coined as black ( or white?) magic.

A look at some tutorials (http://xritephoto.com/ph_learning.aspx, http://xritephoto.com/ph_learning.aspx?action=guide) for X-Rite's i1Profiler, or at the descriptions that come with the Argyll Color Management suite, may also help to understand better what happens in the process of profile generation.

Cheers,
Bart
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ErikKaffehr

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Re: A few questions about camera profiles
« Reply #7 on: February 13, 2014, 06:02:31 am »

hi Bart,

I am somewhat familiar with profiling as I have been making profiles for both scanners and printers, but I am a bit confused. The intention of a profile is generally to specify conversion to a 'connection space' that is to my understanding normally CIE XYX.

ICC profiles are normally definied by primaries, or colorants as far as I understand but cameras are quite different.

Another interesting question is profiling. Camera gamuts are very wide as they are sensitive to pretty much the whole visible spectrum. So a very large color gamut is needed for handling in camera colour. Using a printed target like Faust targets cannot cover the much larger sensor colour space as both traditional and chromogenic printing has quite small gamut.

It is very much possible that the ColorCheckerSG card has a wider gamut but the normal ColorChecker fits almost entirely in sRGB.


I am not so much looking for the answers but I hope to see a discussion about different approcahes, which would broaden our understanding of profile generation and usage.

Best regards
Erik
Hi Erik,

Since you are referring to the new PhaseOne IQ250 ICC profile, as used in CaptureOne, I think the DNG profile info you already got is not going to answer your questions fully. Do note that the DNG profiles used in LR/ACR are something different from ICC profiles.

Although they may use a different starting point (e.g. a monochromator), I think PhaseOne starts out by shooting an image (more likely a series at different exposure levels) of a Digital ColorChecker SG chart, which uses 140 color patches instead of the 24 of a common, or Passport, Colorchecker. They could also use an IT8 standard chart, e.g. one from Wolfgang Faust (http://www.targets.coloraid.de/) which are usually of high quality.

Shooting such a target requires a very neutral shooting environment/studio/lab, because we do not want any ambient light influences/reflections to be mixed in with the main illuminant's spectral output. Also surface reflections from the illuminants must be minimized as much as possible (as in a good repro setup), since that will reduce the saturation of the patches and produce over-saturated/compensated results, and light-fall off must be miniimized.

The chart comes with an accompanying reference data set (usually as a file that comes with the profiling software, or one can read the actual chart colors with a spectrophotometer), and the profiling software will then compare the camera's recorded colors after White Balancing and demosaicing with the target colors, adjust the input and create look-up tables that convert the Raw demosaiced data into the desired/expected input data. That calibrated data can then be converted with a Profile to the Working space and finally to the Output colorspace. Such profiles are Scene referred profiles, and as such well suited for transformations through the imaging chain when the other components are also well profiled. The only drawback is that they are most accurate for the exact same lighting conditions as existed during shooting of the target. The more the actual scene lighting conditions differ, the more inaccuracies can develop (but then we usually do not want accurate colors but rather pleasing colors anyway, and our eyes do not respond exactly the same as RGB trichromatic sensors either).

The software that creates the (calibration) lookup tables and ICC profile, can influence/adjust several things in the creation of that profile, which will e.g. result in more (or less) contrast and saturation. But it also allows to shift the accuracy of interpolation for certain color ranges or even the response for those colors which can shift their colors, but at the same time compress or expand other colors. It is also possible to adjust the colors of the Raw demosaiced input file for the profiling software, which will then try to compensate in the opposite direction.

Camera profiles (ICC type) just translate from one set of coordinates to an other set of coordinates, and there are several almost lossless conversions between coordinates systems possible. XYZ or L*a*b are common device independent coordinate systems, and it is possible to convert calibrated RGB colors into and from those coordinates.

I think a lot of it is solid math, although the math is adjustable to allow and deal with imperfect (trichromatic) input and match with spectrally accurate data, which is already a bit of magic (some profilers produce better results than others, so it's not straightforward calculus). But the result will not be perfect, and the tweaking that will then be done could be coined as black ( or white?) magic.

A look at some tutorials (http://xritephoto.com/ph_learning.aspx, http://xritephoto.com/ph_learning.aspx?action=guide) for X-Rite's i1Profiler, or at the descriptions that come with the Argyll Color Management suite, may also help to understand better what happens in the process of profile generation.

Cheers,
Bart
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ErikKaffehr

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Re: A few questions about camera profiles
« Reply #8 on: February 13, 2014, 06:09:47 am »

Hi Jeff,

Getting back to DNG profiles. It is my understanding that the camera profiles are built using solid color science, spectral data and a bit magic. In general I have been quite happy with Adobe Standard profile on my Sonys but not happy att all with the standard profile for my P45+.

So I generated a dual illuminant profile using the Adobe DNG Profile Editor. My understanding is that I still use the Adobe Standard Profile but making adjustments to it. So calibration is not based on my 24 ColorChecker patches but on all inputs used for the Adobe Standard profile plus my adjustments. Is that correct?

Best regards
Erik
Well, if you are referring to DNG profiles, well, it's complicated...

By default, when you open an image in ACR/LR, the metadata is read from the camera and ACR/LR picks a white balance starting point based on the metadata. If the WB is between the dual illuminates, ACR/LR interpolates between the dual illuminates. As you adjust the WB, the modifications are previewed. So, the way the DNG profile works is to first convert from camera color and then into the working space by way of the DNG profiles and the white balance selected and then transform the preview into the display color space (again using, I think, CIE XYZ). A lot of under the hood stuff happens up to the point where you process...it's pretty messy under that hood, Eric tried to explain some of it to me, but it made my eyes glaze over :~)

The final images after running through the pipeline is then transformed to the output profile selected. In ACR 8.x in Photoshop CC, that output profile can be any ICC profile including RGB, Lab, CMYK or grayscale. In LR only RGB color profiles are supported.
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Vladimirovich

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Re: A few questions about camera profiles
« Reply #9 on: February 13, 2014, 08:33:40 am »

Camera gamuts
purists shall come and say that camera does not have a gamut
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Vladimirovich

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Re: A few questions about camera profiles
« Reply #10 on: February 13, 2014, 08:42:32 am »

So I generated a dual illuminant profile using the Adobe DNG Profile Editor. My understanding is that I still use the Adobe Standard Profile but making adjustments to it.

you are always using some selected base profile (that's how Adobe tries to prevent you from getting absolutely ugly results - and one of the reasone why hoi polloi is running around screaming how good they are in building dcp profiles with a sub $100 24 patch target using simple tools... unlike building non dcp profiles where you do not have hidden suspenders in most/all cases).


So calibration is not based on my 24 ColorChecker patches but on all inputs used for the Adobe Standard profile plus my adjustments. Is that correct?

http://forums.adobe.com/message/1219195#1219195

http://forums.adobe.com/message/5198903#5198903

http://forums.adobe.com/message/3179876#3179876

http://forums.adobe.com/message/3395534#3395534

http://forums.adobe.com/message/3861785#3861785

 http://forums.adobe.com/message/5299746#5299746

http://forums.adobe.com/message/4706036#4706036

http://www.luminous-landscape.com/forum/index.php?topic=56863.msg461536#msg461536

http://www.luminous-landscape.com/forum/index.php?topic=30747.msg249068#msg249068
« Last Edit: February 13, 2014, 08:48:17 am by Vladimirovich »
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hjulenissen

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Re: A few questions about camera profiles
« Reply #11 on: February 13, 2014, 08:45:15 am »

Camera gamuts are very wide as they are sensitive to pretty much the whole visible spectrum. So a very large color gamut is needed for handling in camera colour. ...
Not sure that I agree. An achromatic camera might be sensitive to a broad spectrum, but would you need large color gamut for handling its colour?

I would rather think that a large color gamut is needed for handling files that stem from cameras with narrow pass-bands (little overlap).

So what is being said in this thread is that my humble xrite passport is a waste of time and money? I do feel that I have more "accurate" color now than either Adobe or camera manufacturers can provide. Granted, I do believe that what anyone claims to be a truth based on subjective impressions should be treated with a pinch of salt (that includes my own impressions of color accuracy).

-h
« Last Edit: February 13, 2014, 08:47:34 am by hjulenissen »
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Vladimirovich

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Re: A few questions about camera profiles
« Reply #12 on: February 13, 2014, 01:48:02 pm »

An achromatic camera might be sensitive to a broad spectrum, but would you need large color gamut for handling its colour?

if "I" decide to do a color transform of a certain kind then yes... "I" am who decides how to do the mapping and "I" might do some exotic ones, taste regardless
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Vladimirovich

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Re: A few questions about camera profiles
« Reply #13 on: February 13, 2014, 01:52:15 pm »

So what is being said in this thread is that my humble xrite passport is a waste of time and money?

depends on your goal... if you are trying to account for some unusual light then probably makes sense to some extent, however if you are dealing with a regular light then what you really is doing it is not a creation of an "accurate" profile, but rather you are just getting rid of Adobe's color rendering (LUTs) that they (whoever, Eric, etc) decided is good for populus and put in their profiles, that's it... and then why not just edit the profile directly in Adobe PE ? or gut it with dcptool ? or both ? some more advanced folks (like VitNovak from adobe forums) even have their own software for dcp profiles creation.

« Last Edit: February 13, 2014, 01:54:11 pm by Vladimirovich »
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ErikKaffehr

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Re: A few questions about camera profiles
« Reply #14 on: February 13, 2014, 02:18:41 pm »

Hi,

I made the interesting observation that although the Adobe Standard profile was decently accurate on the ColorChecker it turned out some bad color on my first test shot. I did a calibration with Adobe DNG Profile Editor and got a good colour conversion with slightly improved accuracy.

So this calibration was completely mechanical, now tuning at all.



I have done a lot of testing since than,some of it described here: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/79-p45-colour-rendition , but I decided to stay with LR 5.3 which suits me much better than C1.

My guess is that there may here are the Delta E mean values according to Imatest (sigma in paranthesis):

Capture One: 7.45 (8.4)
Adobe Standard (P45+): 5.65 (6.5)
DNG Profile Editor: 4.71 (5.31)

Adobe Standard (SLT 99): 4.1 (4.52)

For completeness: I did some manipulation in DNG Profile Editor later, reducing saturation on yellowish greens and moving from yellow to green.

But, I got a hint from Iliah that my initial shot used for calibration was bad so I made a new one with better controlled conditions and that is the one I am using on the P45+ now. That one is untouched.

As you have pointed out, DNG Profile Editor just tweaks the base profile, so I was in no way creating a profile from scratch. That is also the reason I still use Adobe Standard profile on the SLT, if it ain't broken why fix it?

By the way, Jeff posted a message where he said that Adobe Standard was less than optimal on his P65+, but he generated a DNG profile and was perfectly happy. I guess that there may be sample variation in P45+ that is contained in the calibration data in the raw files.

Best regards
Erik


depends on your goal... if you are trying to account for some unusual light then probably makes sense to some extent, however if you are dealing with a regular light then what you really is doing it is not a creation of an "accurate" profile, but rather you are just getting rid of Adobe's color rendering (LUTs) that they (whoever, Eric, etc) decided is good for populus and put in their profiles, that's it... and then why not just edit the profile directly in Adobe PE ? or gut it with dcptool ? or both ? some more advanced folks (like VitNovak from adobe forums) even have their own software for dcp profiles creation.


« Last Edit: February 13, 2014, 06:02:51 pm by ErikKaffehr »
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Vladimirovich

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Re: A few questions about camera profiles
« Reply #15 on: February 13, 2014, 04:58:21 pm »

I made the interesting observation that although the Adobe Standard profile was decently accurate on the ColorChecker it turned out some bad color on my first test shot.

define "bad color" ? if you don't like it then you goal was to get rid of Adobe's idea of what colors shall be in some specific area (some reds or whatever) and then shooting a target is accomplishing just that (and not actually building a genuinely new profile from scratch - unless you are using tools that do not start from Adobe's base profiles at all), but then you could just change those colors in Adobe PE directly and/or play with dcp content using dcptool... now what was your goal really and did you achieve it consciously or just tried and liked, but w/o understanding of what happened really ? no offense meant
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ErikKaffehr

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Re: A few questions about camera profiles
« Reply #16 on: February 13, 2014, 05:44:12 pm »

Hi,

The flower in my sample was red, but was reproduced as bluish red on the P45+. With the Sony Alpha 99 it reproduced correctly. In both cases using Adobe standard profile with each camera.

I than shot a ColorChecker and generated a DCP profile (based on the Adobe standard profile), using Adobe DNG Profile Editor. I did nothing to that profile at this stage and it reproduced the red flower as a red flower.

Adobe Standard profile did in this case not give the same rendition on the P45+ as on the Alpha 99, although Delta E on the ColorChecker was pretty good.

At this stage I did no tweaking manually at all. The profiles I am using now are all generated from ColorChecker exposures with no manipulation.

I am essentially satisfied with colour rendition on the Sony Alpha, so I use the Adobe Standard profile with that camera. Delta E is pretty decent on that one, too.

Best regards
Erik


define "bad color" ? if you don't like it then you goal was to get rid of Adobe's idea of what colors shall be in some specific area (some reds or whatever) and then shooting a target is accomplishing just that (and not actually building a genuinely new profile from scratch - unless you are using tools that do not start from Adobe's base profiles at all), but then you could just change those colors in Adobe PE directly and/or play with dcp content using dcptool... now what was your goal really and did you achieve it consciously or just tried and liked, but w/o understanding of what happened really ? no offense meant
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ErikKaffehr

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Re: A few questions about camera profiles
« Reply #17 on: February 13, 2014, 06:04:33 pm »

Hi,

Pretty much my understanding. Nice to have it confirmed.

Best regards
Erik

you are always using some selected base profile (that's how Adobe tries to prevent you from getting absolutely ugly results - and one of the reasone why hoi polloi is running around screaming how good they are in building dcp profiles with a sub $100 24 patch target using simple tools... unlike building non dcp profiles where you do not have hidden suspenders in most/all cases).


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Vladimirovich

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Re: A few questions about camera profiles
« Reply #18 on: February 13, 2014, 06:31:17 pm »

Hi,

The flower in my sample was red, but was reproduced as bluish red on the P45+. With the Sony Alpha 99 it reproduced correctly. In both cases using Adobe standard profile with each camera.

I than shot a ColorChecker and generated a DCP profile (based on the Adobe standard profile), using Adobe DNG Profile Editor. I did nothing to that profile at this stage and it reproduced the red flower as a red flower.

Adobe Standard profile did in this case not give the same rendition on the P45+ as on the Alpha 99, although Delta E on the ColorChecker was pretty good.

At this stage I did no tweaking manually at all. The profiles I am using now are all generated from ColorChecker exposures with no manipulation.

I am essentially satisfied with colour rendition on the Sony Alpha, so I use the Adobe Standard profile with that camera. Delta E is pretty decent on that one, too.

Best regards
Erik



I think p45+ profile (Adobe Standard) is an quite old tech = matrix part doing the main color transform work + single ProfileLookTableData 3D LUT being applied postexposure corrections (and created who knows when and not recently reprofiled - what if P1 did some changes for P45+ CFAs during the life of the line ? ) while Sony A99 profile is the recent created w/ whatever current state of Adobe's tech is
« Last Edit: February 13, 2014, 06:33:37 pm by Vladimirovich »
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ErikKaffehr

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Re: A few questions about camera profiles
« Reply #19 on: February 13, 2014, 06:47:14 pm »

Hi,

The approach solved my problem. I don't know if Phase One made changes to CFA on the P45+ but Kodak may have done that or simply have inconsistent CFAs. As far as I know Phase One does a long calibration of each back (several hours), I presumed that may include spectral calibration, too. But perhaps they just map out bad pixels/columns.



Best regards
Erik

I think p45+ profile (Adobe Standard) is an quite old tech = matrix part doing the main color transform work + single ProfileLookTableData 3D LUT being applied postexposure corrections (and created who knows when and not recently reprofiled - what if P1 did some changes for P45+ CFAs during the life of the line ? ) while Sony A99 profile is the recent created w/ whatever current state of Adobe's tech is
« Last Edit: February 13, 2014, 06:49:30 pm by ErikKaffehr »
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Erik Kaffehr
 
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