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Author Topic: What is ACR calibration REALLY doing?  (Read 61277 times)
Barry Pearson
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« on: May 24, 2007, 12:09:24 PM »
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A recent article posted here appears to assume that the purpose of calibrating ACR, (and by extension, Lightroom), using scripts such as the Thomas Fors script, is to cater for differences between cameras of the same model. I disagree!

The article said "they assume that the camera that was used to create the raw processor's profile and your particular camera of the same model have the exact same colour characteristics.... Or, it might be such that the generic profiling done by Phase One, Adobe, or someone else varies enough from what your particular camera does so as to make the creation of a custom profile (or as will be seen, an edited version of that profile) worth having".
http://www.luminous-landscape.com/reviews/...ib-profil.shtml

I believe that the primary purpose of calibrating ACR or Lightroom using such a script is that the default Adobe method of calibration gives results that are unacceptable to many people, while the use of such a script gives results that many of those people prefer. To be very simplistic indeed, these scripts correct the Adobe tendency to give reds that are too orange, and grass that is too yellow.

Have a look at the many results of using such scripts for many camera models that have been published in various forums. They nearly always have a significantly negative Red Hue, and a significantly positive Red Saturation. (The values in the article are respectively: -9; 20). This tendency is obviously systematic, and not to do with within-model variations which would give values either way. I suspect that using such a script on the ACTUAL cameras that Adobe used originally would also give such results!

Here are some results that have been published in various forums:
D200: Red Hue: -24; Red Saturation: 42
D2X: Red Hue: -20; Red Saturation: +20
K100D: Red Hue -27; Red Saturation 40
K10D: Red hue: -13; Red sat: 7              (mine)
*istD: Red Hue: -24; Red Saturation: 27       (mine)
*istDS: Red hue: -26; Red Sat: +35
LX1: red hue -20; red saturation +42
LX1: Red hue: -26; Red sat: +19
A2: Red hue: -26; Red sat: 0
G3: Red hue: -1; Red sat: 20
300D: Red hue: -5; Red sat: 20
20D: Red hue: -9; Red sat: 9
10D: Red hue: -5; Red sat: 30
5D: Red hue: -5; Red sat: 11
5D: Red hue: -11; Red sat: 4

These are not results from anti-Adobe people, or people with no knowledge of colour management. These are typically results from people who own a GretagMacbeth ColorChecker, who care enough about their colour balance to use the ColorChecker and a suitable script to try to get things right, and who then share their results so that others can benefit. We don't have all the answers, but surely we can raise serious questions!
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Schewe
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« Reply #1 on: May 25, 2007, 12:11:44 PM »
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I believe that the primary purpose of calibrating ACR or Lightroom using such a script is that the default Adobe method of calibration gives results that are unacceptable to many people, while the use of such a script gives results that many of those people prefer. To be very simplistic indeed, these scripts correct the Adobe tendency to give reds that are too orange, and grass that is too yellow.
[a href=\"index.php?act=findpost&pid=119407\"][{POST_SNAPBACK}][/a]

No...the primary reason for the calibrate tab is to account for variations between sensor lots of a given brand and model of camera. Bruce Fraser and I tested 3 Canon Rebels and found considerable variation in both ISO and color rendering. They required 3 different calibrate settings to bring them all into agreement. And, that's just 3 cameras from the same model-two of the serial numbers on the cameras were close (which means they were "probably" from the same sensor lot).

What this points to is I think there is a WIDE variation between sensors, even in the same lot and same model...perhaps the camera makers ARE doing sensor by sensor adjustments in their proprietary and undocumented file formats-we don't know since it's proprietary and undocumented...and perhaps this is why SOME people feel that the camera software does a more accurate rendering of color than 3rd party software. And this is something the camera makers may not want to admit. I don't know since THEY are staying mum on the whole issue.

This may change in the future...we can only hope. Kodak, when they first shipped a digital camera shipped a "Cal File" that was the calibration file for THAT camera and THAT sensor that was used to make sure the sensor was within spec and provided a method of finger printing that sensor's responce...I think something along these lines, embedded in the capture and metadata is going to be what is required eventually. But all this proprietary business seems to have gotten in the way of a standard method exchanging data on the sensor by sensor variations that we all know occur.
« Last Edit: May 25, 2007, 12:13:33 PM by Schewe » Logged
bjanes
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« Reply #2 on: May 25, 2007, 12:46:28 PM »
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No...the primary reason for the calibrate tab is to account for variations between sensor lots of a given brand and model of camera. Bruce Fraser and I tested 3 Canon Rebels and found considerable variation in both ISO and color rendering. They required 3 different calibrate settings to bring them all into agreement. And, that's just 3 cameras from the same model-two of the serial numbers on the cameras were close (which means they were "probably" from the same sensor lot).

What this points to is I think there is a WIDE variation between sensors, even in the same lot and same model...
[{POST_SNAPBACK}][/a]

There might well be considerable variation in sensors as Jeff asserts, but testing of 3 samples of one camera model does not constitute a statistically significant model for the universe of sensors. There may well be variation between CMOS and CCD or among other manufacturers such as Sony, Dalsa, and Kodak.

[a href=\"http://www.dpreview.com/reviews/nikond40/page17.asp]DPReview[/url] routinely tests the ISO sensitivity of cameras as a part of their testing procedure. The Nikons are usually spot on for ISO whereas Canon often gives a bit more sensitivity than nominal. Not a lot of ISO variation in these tests. Of course these are tests of the camera system and not of the sensor in isolation.

Bill
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madmanchan
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« Reply #3 on: May 25, 2007, 02:28:43 PM »
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To answer the technical question posted in the title of the thread:

As the article notes, there are two profiles built-into ACR for each supported camera: one for illuminant D65, one for illuminant A. These are matrix-based profiles. Adjusting the ACR calibration knobs moves the actual RGB primaries used in the built-in ACR camera profiles.
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Schewe
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« Reply #4 on: May 25, 2007, 02:35:12 PM »
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There might well be considerable variation in sensors as Jeff asserts, but testing of 3 samples of one camera model does not constitute a statistically significant model for the universe of sensors.
[a href=\"index.php?act=findpost&pid=119597\"][{POST_SNAPBACK}][/a]

Obviously...but it does suggest that even with a single model and two sensors whose serial numbers were very close, one should assume there WILL be variations from camera to camera, which is why Thomas put the calibrate function in Camera Raw in the first place. And why Kodak shipped each of their cameras with cal files...I know of no other cameras (other than medium format backs) that are doing that openly.
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Barry Pearson
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« Reply #5 on: May 25, 2007, 05:27:47 PM »
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No...the primary reason for the calibrate tab is to account for variations between sensor lots of a given brand and model of camera. [{POST_SNAPBACK}][/a]

That doesn't answer my question, and doesn't respond to the point I made about the near-universal trends of Red Hue and Red Saturation.

Yes, I KNOW that the Calibration tab is intended to cater for differences between specific cameras. But its use has revealed something more significant.

Calibrating using the Fors script, or probably any other, IS NOT primarily catering for differences between specific cameras. If that is what they were doing, there would be a spread of Red Hue and Red Saturation from positive to negative. They would NOT be clustered with significant negative Red Hue and significant positive Red Saturation.

The best proof would be to test the ACTUAL cameras that Adobe used for generating the ACR profiles using the Fors script. My prediction is that they would consistently show a significant negative Red Hue and significant positive Red Saturation. But without access to those cameras, I can't test this for myself.

Many people in forums have complained that the default ACR settings give reds that are too orange, and grass (etc) that is too yellow. (In some quarters, this has become a joke!) That was my own problem until I used the Fors script to calibrate my first dSLR a couple of years ago, and then my latest more recently. These issues can be compensated for by a significant negative Red Hue and significant positive Red Saturation. And the Fors script will tell people to use those. Since using the Fors script, I no longer have that type of problem.

There is a SECONDARY affect of the scripts - catering for within-model variations. In the examples I published at the start of this thread, there were differences even for the same camera model. No one doubts that this is ALSO an issue. But the MAIN issue is that the standard Adobe method of profiling cameras give results that many people don't like, and the Fors script, and others, deliver better results for those people.

Anyone doubting what the scripts are doing needs an answer to the systematic biased results for Red Hue and Red Saturation. I posted some links to sources of those results at:
[a href=\"http://adobe.groupbrowser.com/t165599.html]http://adobe.groupbrowser.com/t165599.html[/url]
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Barry Pearson
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« Reply #6 on: May 25, 2007, 05:40:09 PM »
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As the article notes, there are two profiles built-into ACR for each supported camera: one for illuminant D65, one for illuminant A. These are matrix-based profiles. Adjusting the ACR calibration knobs moves the actual RGB primaries used in the built-in ACR camera profiles.
[{POST_SNAPBACK}][/a]

Yes, I am aware of that, since it is documented in the DNG specification which I know a lot about:
[a href=\"http://www.barrypearson.co.uk/articles/dng/]http://www.barrypearson.co.uk/articles/dng/[/url]

Also in the DNG specification are tags called CameraCalibration1 and CameraCalibration2, specifically for within-model variations. I would like to be able to convert to DNG and add those fields to my DNGs for my particular cameras, and so avoid the need for the Calibration tab. (This would, I hope, mean that the resultant DNGs would be equally applicable to all raw converters that accepted DNGs with their embedded profile).

So what I want to be able to do is calibrate my cameras and feed the results into the Adobe DNG Converter (or equivalent) to create values for those tags.
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bjanes
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« Reply #7 on: May 25, 2007, 07:16:30 PM »
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Obviously...but it does suggest that even with a single model and two sensors whose serial numbers were very close, one should assume there WILL be variations from camera to camera, which is why Thomas put the calibrate function in Camera Raw in the first place. And why Kodak shipped each of their cameras with cal files...I know of no other cameras (other than medium format backs) that are doing that openly.
[a href=\"index.php?act=findpost&pid=119613\"][{POST_SNAPBACK}][/a]

The ACR calibration appears to be matrix based. Most camera calibration profiles that I am aware of involve lookup table based profiles and may work well only under controlled conditions and can be quite large. What type of profiles are provided with the Kodak and medium format cameras?
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Schewe
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« Reply #8 on: May 26, 2007, 11:53:48 AM »
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What type of profiles are provided with the Kodak and medium format cameras?
[a href=\"index.php?act=findpost&pid=119657\"][{POST_SNAPBACK}][/a]

I don't know that the Kodak "cal files" were real profiles in a standard sense. Pretty sure they were just "reports" in text form of the results of a battery of tests-and not a whole lot of them either-just the basics. Leaf, Phase One and Imacon backs have embedded metadata calibration stats as well.

But if the camera makers could develop a "standard" (ooops, there's that concept again) ISO & color test array and write the results in metadata and document it, it would go a long way towards bringing about camera standards. But they seem more intent on their "LOOK".

Some of their attitudes may be changing though. If you look at the rate of progress and change in the industry, it's slowed way down. Neither Nikon nor Canon are churning out new models nearly as fast as they were. Part of that is the fact that there's not a whole lot left to stuff into a DSLR and part of it is the fact that pretty much everybody who needs a camera has one so they are competing not only against themselves (upgrades to existing cameras) but each other.

I don't know when...but at some point, some smart guy in Tokyo will realize that adopting a standard before the next guy might lead to some additional sales.

We can only hope...

:~)
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John Sheehy
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« Reply #9 on: May 26, 2007, 08:01:18 PM »
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DPReview routinely tests the ISO sensitivity of cameras as a part of their testing procedure. The Nikons are usually spot on for ISO whereas Canon often gives a bit more sensitivity than nominal. Not a lot of ISO variation in these tests. Of course these are tests of the camera system and not of the sensor in isolation.

[a href=\"index.php?act=findpost&pid=119597\"][{POST_SNAPBACK}][/a]

They are tests of the metering, AFAIK.  what a camera meters for, and what its sensitivity is (either saturation-based, or noise-based) may be different yet.

I bought a 30D that I returned for an exchange.  It metered like my 20D, but it amplified the input going into the ADC 1/3 stop too high, losing 1/3 stop of potential DR in the highlights.  Its histogram of a flat wall was at the 55% mark.  My other Canons generally fall at the 45% mark on the histogram (green channel or luminance).
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eronald
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« Reply #10 on: May 27, 2007, 07:05:15 AM »
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A plague on both their houses ! (Shak.)

Yes, Jeff, a "standard" is what Adobe says it is ?  Adobe refuses to play nice with the ICC input profile standard, preferring something Thomas cooked up on vacation. We've already had plenty of people flame me on that so, yes, I have read, reread and probably even understand the color rendering parts of the DNG code. And it still fails to impress me. It's not that it's wrong, it's that it's not enough. And, yes, I've told Thomas that in person, and so have a few other people in the industry.

Adobe is trying to commoditize the cameras, so of course they want all cameras to look equal, like Microsoft wants all Windows hardware boxes to look equal. That way Adobe gets all the money, the camera makers do all the nasty physical work matching the physical things to what the software already expects. I'm not saying this is necessarily bad, but it does crimp innovation a bit.

The camera makers are going the other way, hoarding data on their hardware like the crown jewels making life unpleasant for anyone writing Raw conversion software. Also they doubtless find that careful calibration and linearization is more trouble than it is worth for consumer models like the Rebel and the 5D. From reports out there by users of my profiles there is at least half a stop variation in exposure alone in the 5D population. The high end models are usually a bit better matched.

Last not least, anyone who has measured Colorcheckers knows that matching charts is not what Gretag does best - I own Colorcheckers that are *immediately and visibly different*; as they told me one day "we have had production problems". This also accounts, no doubt, for some of the variation in the results of the calibration script.

Of course, every amateur who photographs a chart has perfect lighting and no reflections, yeah !

Edmund

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I don't know when...but at some point, some smart guy in Tokyo will realize that adopting a standard before the next guy might lead to some additional sales.

:~)
[a href=\"index.php?act=findpost&pid=119723\"][{POST_SNAPBACK}][/a]
« Last Edit: May 27, 2007, 07:43:46 AM by eronald » Logged

Edmund Ronald, Ph.D. 
bjanes
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« Reply #11 on: May 27, 2007, 08:14:28 AM »
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They are tests of the metering, AFAIK.  what a camera meters for, and what its sensitivity is (either saturation-based, or noise-based) may be different yet.

I bought a 30D that I returned for an exchange.  It metered like my 20D, but it amplified the input going into the ADC 1/3 stop too high, losing 1/3 stop of potential DR in the highlights.  Its histogram of a flat wall was at the 55% mark.  My other Canons generally fall at the 45% mark on the histogram (green channel or luminance).
[{POST_SNAPBACK}][/a]

DPreview does not describe their testing process in detail, but in addition to exposing according to the camera light meter, they expose a gray card according to a reading taken by their Sekonic L-358 hand held meter. If a gray card is exposed under specified conditions, the ISO 12232 saturation speed can be determined as
[a href=\"http://www.normankoren.com/digital_cameras.html]Norman Koren on Digital ISO[/url] explains. With exposure under these conditions an "18% gray card has a voltage or pixel level 18/106 of full scale (e.g., a pixel level of 696 at the output of a 12-bit A-to-D converter, which can represent 4096 levels). In an 8-bit color space encoded for display at gamma = 2.2 (sRGB, Adobe RGB, etc.), the corresponding pixel level is 114 (from the formula, 255*(18/106)(1/2.2) )."

This exposure under specified conditions does not involve the camera's light meter and determines the effective ISO of the camera system, which includes the sensor as well as the amplifier and A-to-D converter, as I mentioned in my previous post. If the pixel level in a gamma 2.2 space with the specified exposure is 114, then the camera system ISO is on spec. If the results of the standardized exposure do not match the results of an exposure using the camera's meter, then the meter is defective.

Bill
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bjanes
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« Reply #12 on: May 27, 2007, 08:31:25 AM »
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A plague on both their houses ! (Shak.)

Yes, Jeff, a "standard" is what Adobe says it is ?  Adobe refuses to play nice with the ICC input profile standard, preferring something Thomas cooked up on vacation. We've already had plenty of people flame me on that so, yes, I have read, reread and probably even understand the color rendering parts of the DNG code. And it still fails to impress me. It's not that it's wrong, it's that it's not enough. And, yes, I've told Thomas that in person, and so have a few other people in the industry.

[a href=\"index.php?act=findpost&pid=119800\"][{POST_SNAPBACK}][/a]

Edmund,

Adobe does not use a standard ICC profile in their calibration as is done by Capture One and some other raw converters. This has been discussed at length previously by such experts as Bruce Fraser, and the consensus is that such profiling may be useful under controlled studio conditions, but does not work well in general photography.

If you use a lookup based profile under controlled conditions, it is possible to match a  target such as the ColorChecker SG reasonably well. If you use a matrix based profile, then you are determining the coefficients for converting from camera CIE XYZ to working space CIE XYZ, and accurate color matching depends on the linearity of the color filters in the camera sensor. If the filters were perfectly linear, then an exact match could be obtained according to Thomas Knoll. Since the filters are not perfect, then a color match may not be attainable for some colors.

Thomas has chosen a calibration method that works well for most users, but if it does not meet your needs, why don't you use Capture One or some other converter that does use ICC profiles?

Bill
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Barry Pearson
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« Reply #13 on: May 27, 2007, 10:40:59 AM »
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In my original post for this thread, I pointed out that using the Thomas Fors script appears to result in negative Red Hues, and positive Red Saturations. (In fact, I have never seen a positive Red Hue, or a negative Red Saturation, in many results - more than just the ones in the original post - I've seen posted to forums after using this script!)

Furthermore, and obviously important, people appear to prefer the result of using the Calibrate tab values identified by running the script. It typically improves a problem that a number of people have complained about in forums, that the default Adobe profiles give reds that are often too orange, and greens that are often too yellow.

If true, then this offers the chance of identifying generic Calibrate tab values per camera model, which would help people without a GretagMacbeth ColorChecker, and/or people who use Lightroom but don't have ACR+Photoshop. We could have camera-model presets for ACR or Lightroom. (Or an evolution of Adobe's profiling).

I've just started a thread in Thomas Fors' forum for the AcrCalibrate script:
http://groups.google.com/group/acrcalibrat...5020c77c83e07dd

In it, I asked that people post their results from running this script, and say whether they prefer the results to the default Adobe value. I repeat that request here:

Please post (here or there) your results from running the Thomas Fors script (or the Rags Gardner one, etc). Let's gather more data to see whether this effect is real, and to draw some conclusions.
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Schewe
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« Reply #14 on: May 27, 2007, 01:07:13 PM »
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Adobe is trying to commoditize the cameras, so of course they want all cameras to look equal, like Microsoft wants all Windows hardware boxes to look equal. That way Adobe gets all the money, the camera makers do all the nasty physical work matching the physical things to what the software already expects. I'm not saying this is necessarily bad, but it does crimp innovation a bit.
[a href=\"index.php?act=findpost&pid=119800\"][{POST_SNAPBACK}][/a]

Ya know, you "think" you know what Adobe is trying to do, but you're not even sneaking up on having half a clue doode.

Adobe is doing DNG because Thomas Knoll thinks it's the right thing for the industry. There is no money in developing DNG. They aren't making any money on DNG now and they don't expect to in the future. There is no money changing hands when a camera vendor uses DNG nor when a user converts to DNG. You have it in your head that's DNG is an attempt by Adobe to engage in monopolistic practice? Well, that's YOUR baggage you're bringing to the table.

There was exactly one guy-Thomas Knoll-that came up with the concept and idea of producing a raw file format standard. Not to make money...Thomas doesn't need to make money in that way. He thought it was the right thing to do for the photo industry. I happen to believe he's correct.

Other than Dave Coffin and perhaps Eric Bibble, there's nobody else on the planet that has as much knowledge and experience in dealing with raw file formats. He's already worked with Coffin, and Eric is a story "not for public consumption".

There is one other guy that also has a lot of experience dealing with raw file formats-Michael Jonnson-formerly of Phase One then pixmantic. He's also now working on Camera Raw/DNG along with Zalman Stern (who used to work on Photoshop then spent a decade or so at Macromedia).

You keep talking like there's this big attempt in the boardrooms at Adobe to plot to "commoditize" camera maker's file formats...uh, no. You simply couldn't be further than the truth.

Adobe is just trying to do the right thing when it comes to the long term conservation and preservation of digital files and that includes PDF-A as well as DNG and the old and venerable (although some say outdated) Tiff.

If you want to see an example of Adobe's true motives, look at what Adobe did for the ISO regarding Tiff-EP. They granted the ISO the right (and waived or set aside their patent rights) to incorporate Tiff-EP as a public standard-which was turned around and adopted by Nikon and Canon for their proprietary and undocumented file formats-see recent NEFs and CR2s are so close to being DNG by virtue of being rather fully formed Tiff-EP files that the big joke is that NEFs and CR2s are already DNGs except for the standardized location of metadata and meaning of the metadata.

You may think you know what Adobe is trying to do-but you don't. And, it would be real useful if you did get a clue pretty quick cause misstating Adobe's motive simply gives aid and comfort to the enemy...undocumented and proprietary file formats.

The sooner the photo industry realizes just how dangerous proprietary and undocumented file formats are to the future of the photo industry, the sooner the camera companies will be forced to address the issue.
« Last Edit: May 27, 2007, 01:09:46 PM by Schewe » Logged
eronald
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« Reply #15 on: May 27, 2007, 01:10:17 PM »
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Bill,
 Disagreeing with a consensus is sometimes a useful strategy, and one with an implicit attraction to a contrarian
 It's an interesting academic question whether it's the separability of the color filters or the non-linearities of the sensor electronics which creates the most practical issues with matrix models. I have heard it said that the high sensitivity of one major vendor's dSLR sensors is incurred at the expense of separability.
 Regardless:  Real engineering will evidence non-linearities, and I believe Thomas relies excessively on the camera makers exposing utopically perfect data. Forcing camera makers to market externally linear devices is a good political strategy for Adobe, but not so useful to present day users.
 I expect that realism and a transition to a more complete model will intervene soon. Of course, Adobe won't be the last company to market a new version as solving some inadequacies that a previous version introduced as a triumphant breakthrough.
 As for your suggestion to use C1 - I find it so good that I have been distributing C1 profiles for the M8 for a few months, and these are in widespread use in the Leica community.
 I have even given a talk about this to Xrite at Regensdorf, who have -with great generosity and a great sense of humor- supported my efforts. The upshot is that as you say chart-based profiling often has issues, but my profiles seem to be useful to many users. We don't know exactly why I happen to be successful practicing an approach that has, as you indicate, often disappointed.

Edmund

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Edmund,

Adobe does not use a standard ICC profile in their calibration as is done by Capture One and some other raw converters. This has been discussed at length previously by such experts as Bruce Fraser, and the consensus is that such profiling may be useful under controlled studio conditions, but does not work well in general photography.

If you use a lookup based profile under controlled conditions, it is possible to match a  target such as the ColorChecker SG reasonably well. If you use a matrix based profile, then you are determining the coefficients for converting from camera CIE XYZ to working space CIE XYZ, and accurate color matching depends on the linearity of the color filters in the camera sensor. If the filters were perfectly linear, then an exact match could be obtained according to Thomas Knoll. Since the filters are not perfect, then a color match may not be attainable for some colors.

Thomas has chosen a calibration method that works well for most users, but if it does not meet your needs, why don't you use Capture One or some other converter that does use ICC profiles?

Bill
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« Last Edit: May 27, 2007, 02:13:36 PM by eronald » Logged

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« Reply #16 on: May 27, 2007, 03:26:18 PM »
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You may think you know what Adobe is trying to do-but you don't. And, it would be real useful if you did get a clue pretty quick cause misstating Adobe's motive simply gives aid and comfort to the enemy...undocumented and proprietary file formats.

The sooner the photo industry realizes just how dangerous proprietary and undocumented file formats are to the future of the photo industry, the sooner the camera companies will be forced to address the issue.
[{POST_SNAPBACK}][/a]

Jeff,

 I certainly don't know much about what is happening at Adobe. Indeed, Adobe is to praise for releasing documentation and source code, and freely licensing DNG. I have publicly apologized in the past because I did not realize initially that DNG is completely freely licensed and some converter code provided.

 However, regarding color models I do think that isssues of digital color have an existing venue for their discussion that happens to be the ICC, which has made a practice of releasing reasonably well documented standards and even sample code. ICC profiles are not closed technology as far as I can see.

 All of us abhor the undocumented file formats. But forcing an incomplete color model on the rest of the industry sounds a bit like burning the village to save it.
 
 I have written an essay entitled [a href=\"http://photofeedback.blogspot.com/2007_02_01_archive.html]Raw: The Adobe Way, The Microsoft Way and the Open Way[/url] which may prove entertaining to some here.

Edmund
« Last Edit: May 27, 2007, 03:28:51 PM by eronald » Logged

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« Reply #17 on: May 27, 2007, 03:52:55 PM »
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Adobe is just trying to do the right thing when it comes to the long term conservation and preservation of digital files and that includes PDF-A as well as DNG and the old and venerable (although some say outdated) Tiff.

If you want to see an example of Adobe's true motives, look at what Adobe did for the ISO regarding Tiff-EP. They granted the ISO the right (and waived or set aside their patent rights) to incorporate Tiff-EP as a public standard-which was turned around and adopted by Nikon and Canon for their proprietary and undocumented file formats-see recent NEFs and CR2s are so close to being DNG by virtue of being rather fully formed Tiff-EP files that the big joke is that NEFs and CR2s are already DNGs except for the standardized location of metadata and meaning of the metadata.
[a href=\"index.php?act=findpost&pid=119859\"][{POST_SNAPBACK}][/a]

I agree with your view there, but I'll clarify and qualify it a bit.

Adobe granted ISO the right to incorporate TIFF 6.0 (which Adobe owns) into a public standard, which became ISO 12234-2 (TIFF/EP).

DNG, and apparently NEF, CR2, and perhaps others, were then based on TIFF/EP. Examine a NEF with "dng_analyse" from the DNG SDK, and it shows its tags and values. I suspect, as you imply, that converting a NEF to a DNG is little more than re-arranging the data and adding the unique DNG camera profile metadata. (For interest, DNG and CR2 both use JPEG lossless compression for the raw image data). Contrary to statements that using DNG would inhibit the innovation of Canon and Nikon, it would probably be pretty trivial for them and be no inhibition at all.

A recent email from the ISO working group revising ISO 12234-2 (TIFF/EP) says: "The Adobe DNG format was derived from this standard and the group has Adobe's permission to incorporate modifications and developments made for DNG in the new standard". Perhaps the next version of ISO 12234-2 will be much closer to DNG?

DNG is, as far as I know, the ONLY raw file format specifically designed to be suitable for archiving. It would be helpful if ISO made that clear, and exploited it, because there are lots of national libraries and archives that would like to adopt an ISO standard archival raw file format. They would nominate DNG immediately if it had ISO's blessing as an archival format. (As the US Library of Congress already has).
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« Reply #18 on: May 27, 2007, 03:57:32 PM »
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I certainly don't know much about what is happening at Adobe. Indeed, Adobe is to praise for releasing documentation and source code, and freely licensing DNG. I have publicly apologized in the past because I did not realize initially that DNG is completely freely licensed and some converter code provided.
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So, why do you insist in characterizing Adobe's reasons for DNG as something south of noble?

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Adobe is trying to commoditize the cameras, so of course they want all cameras to look equal, like Microsoft wants all Windows hardware boxes to look equal. That way Adobe gets all the money, the camera makers do all the nasty physical work matching the physical things to what the software already expects. I'm not saying this is necessarily bad, but it does crimp innovation a bit.

And that is what you said earlier in the thread...this is a halfbaked economic model you are STILL trying to paint Adobe with-even though you now admit Adobe is giving DNG away. You still don't get it.

Unfortuantely, to even answer you tends to give credence to your crackpot ideas-which is why, in the past, I've let you say what you will, knowing full well you didn't have a clue. But you keep coming around and totally misrepresenting what Adobe (ie: Thomas Knoll) is trying to do and why he's trying to do it.

And your "post" regarding Coffin's Dcraw also is wrong. Have you asked Davis what he thinks of DNG? Dcraw actually benefits since he now has color processing data on other cameras where he hasn't had to do the work-Thomas has.

You also pretty much mis-characterize MSFT's efforts at providing raw access via a raw codec. This was MSFT's punt...they bowed to the pressures of the camera makers by letting them keep their stuff under wraps while exposing the default rendered raw file for use in Windows....and only Windows. This isn't some sort of nice thing for the photo industry, this is MSFTs dodge around the whole issue. Apple on the other hand went a different direction by basically using Coffin's Dcraw for both the OS as well as basic raw support of Aperture.

Unfortunately, you write about this stuff as though you know what's going on in the trenches...and you don't. As a result, you end up being part of the problem, not the solution. You are spreading FUD. And, I can't quite figure out why...cause if you THINK you are doing the industry a service, you are wrong-so I can only guess that you have some other agenda...
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« Reply #19 on: May 27, 2007, 04:23:15 PM »
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DNG, and apparently NEF, CR2, and perhaps others, were then based on TIFF/EP. Examine a NEF with "dng_analyse" from the DNG SDK, and it shows its tags and values. I suspect, as you imply, that converting a NEF to a DNG is little more than re-arranging the data and adding the unique DNG camera profile metadata. (For interest, DNG and CR2 both use JPEG lossless compression for the raw image data). Contrary to statements that using DNG would inhibit the innovation of Canon and Nikon, it would probably be pretty trivial for them and be no inhibition at all.
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Absolutely...and I would argue that the reason (at least one big reason) that recent NEF and CR2 formats from newer Nikon and Canon camera _ARE_ better is because of DNG.

I know for a fact that both Nikon and Canon have studied DNG very closely. And while they have yet to bend to pressure to adopt DNG, they HAVE been influenced by DNG if for no other reason to improve their own raw file formats-even if they remain propriatary and undocumented. In other words, DNG has taught them a few things...

I'm not aware of what's going on at the ISO with regards to a TIFF-EP update-other than there's something going on-finally. Which is good news I suppose.
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