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Sam Doran
Currently Being Moderated

Reconvert with new DNG Converter?

Nov 22, 2009 8:11 PM

If I converted a bunch of Canon 7D CR2 files to DNG using DNG Converter 5.5, should I reconvert from the original raw file with 5.6? What is different about the files, since the raw data should remain unchanged?

 

I thought the advantage of using raw/DNG was that the file itself stayed intact and that, as raw processing algorithms get better over time, the data could be "crunched" in different ways to make the image better. I am getting a sense now that some of my DNG files created using older versions of the DNG Converter (I have been using DNG for several years now) are somehow inferior to those created using the latest version of the converter.

 

Any information on this issue is greatly appreciated!

 
Replies
  • Currently Being Moderated
    Nov 23, 2009 8:36 AM   in reply to Sam Doran
    function(){return A.apply(null,[this].concat($A(arguments)))}

    If I converted a bunch of Canon 7D CR2 files to DNG using DNG Converter 5.5, should I reconvert from the original raw file with 5.6?

     


    Supposed you have any reason to use DNG instead of CR2 (for example you are using CS3 or older), then yes, reconvert the files unconditionally, from the CR2, not from the DNG (the new DNG converter would process the old DNG too, but the result would not better than it is now).

     

    function(){return A.apply(null,[this].concat($A(arguments)))}

    What is different about the files, since the raw data should remain unchanged?

     

     

    Caution with "raw data". The raw image data remains the same, but the metadata changes. For example the information regarding the color reproduction is different.

     

    function(){return A.apply(null,[this].concat($A(arguments)))}

    I thought the advantage of using raw/DNG was that the file itself stayed intact and that, as raw processing algorithms get better over time, the data could be "crunched" in different ways to make the image better. I am getting a sense now that some of my DNG files created using older versions of the DNG Converter (I have been using DNG for several years now) are somehow inferior to those created using the latest version of the converter.

     

     

     

    The reason for the reconversion is, that the previous version contained a "preliminary" (quick and really dirty) support for the 7D; there were several errors in the conversion. I guess Adobe will not go that way in the near future.

     

    All that has nothing to do with your older files; you don't have any reason to reconvert them. You may profit from using the best LR/ACR version even with the old files, a reconversion would not add anything to that, rather, you would lose the adjustments, if they were recorded in the DNG file.

     
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  • Currently Being Moderated
    Nov 23, 2009 12:10 PM   in reply to Sam Doran
    function(){return A.apply(null,[this].concat($A(arguments)))}

    I do have the original CR2s, but say I had several DNG files created with 5.5 and then converted them with 5.6; since it is DNG to DNG, the original (inferior) 5.5 metadata is retained. This makes me feel like I have permanently "tainted" files because they were created with 5.5 (though I still have the original CR2s and could reconvert from the originals) and I am forever stuck with what I have


    The current DNG converter does work this way, i.e. it does not replace that metadata (see the thread from Barry Pearson, requesting an option for replacing the metadata). Thus you would stuck with the incorrect metadata if you had not kept the CR2s.

     

    Note, that there is no disadvantage of startiing out from the CR2, because the adjustments saved in the DNG file are not of much use anyway because of the changes. For example the color information has changed; I don't know how big the changes are, but they may require the readjustment of saturation and perhaps even WB. If you have ISO 100 shots (or 125, 250, 500, 1000 - but you should not use franctional ISOs with raw), then the image will become brighter after the new conversion, thus your Exposure, Fill, Brightness, Recovery settings may have to be changed.

     

    function(){return A.apply(null,[this].concat($A(arguments)))}

    Will I get lower quality images from 5.5 DNGs than 5.6 DNGs?


    Yes, but this is a speciality of the too quick and dirty support of the 7D in 5.5, i.e. this is not a generic consideration.

    function(){return A.apply(null,[this].concat($A(arguments)))}

    Should I be more concerned about getting the latest ACR/LR and not worry so much about the DNG Converter version that was used to convert to DNG?


    I have no idea if ACR 5.6 has any functional enhancements compared to 5.5. However, the correct support of 7D raw files in DNG format does not require 5.6 of ACR but of the DNG converter.

     

    For example one of the problems with the preliminary support is the maze-like appearance on smooth surfaces in low ISO shots. The reason is a hardware fault (in cleartext: Canon created crap). This problem can be countered at least partly (I don't know if it goes away totally) with adding a certain metadata to instruct the raw processor to apply a somewhat different processing than normally. This is nothing new, even much older ACR versions do that - if the DNG converter inserted this information.

     

    (The vertical banding in the very shadows of ISO 100 to 400 does not change, like http://www.panopeeper.com/Canon/Canon7D_Banding_ISO00100_Jehuty_DPR_0014 .JPG)

     

    function(){return A.apply(null,[this].concat($A(arguments)))}

    I am only nervous because I do not keep the original CR2s long term, only the DNG. I want to make sure that the DNGs I have created with 5.5 are not in some way inferior in quality before I delete the CR2s. If there is inferior metadata in the 5.5 DNGs, will using the latest version of ACR when it comes out "clean out" this bad metadata in favor of better processing methods, or is the only way to "clean out" the metadata to convert to DNG with the official release of the 5.6 DNG Converter?


    As you have no way of making sure, that the conversion is perfect, it is foolish to delete the original, i.e. the CR2; the rest is speculation.

     

    However, you should not discount the possibility, that another raw processor or another DNG converter (or a later version of Adobe's DNG converter) can make a better processing of the CR2 or a better conversion in DNG.

     

    Gabor

     
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  • Currently Being Moderated
    Nov 24, 2009 10:39 AM   in reply to Sam Doran

    was that PEF to DNG issue w/ DNG converter addressed by Adobe ?

     

    http://forums.dpreview.com/...forums/read.asp?forum=1036&message=32904 790


    "...The program will not work with DNG files converted from PEF's by the current version of the Adobe DNG Converter application due to this program stripping out the necessary black masked-to-light photosites at the right and bottom borders of the sensor in landscape orientation which are used by the correction algorithm..."

    if the claim is correct then people who converted PEF to DNG lost in fact some "raw data", right ?

     
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  • Currently Being Moderated
    Nov 24, 2009 2:23 PM   in reply to deejjjaaaa

    That conversion of K20 PEF files is still erroneous (with 5.6). This is an example for the necessity to keep the original raw file: not only that the conversion is wrong, but it removes data from the "image" (the masked area). This should never happen.

     

    The result is particularly strange, regarded that the output of the Adobe DNG converter from PEF is different niot only from the Pentax native DNG but from the DNG converted from that DNG by the Adobe DNG converter.

     

    Gabor

     
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  • Currently Being Moderated
    Nov 24, 2009 2:33 PM   in reply to Panoholic

    Did Adobe ever comment as to why ? because hell lot of people are running for years around claiming that DNG conversion is safe as FDIC in terms of data preservation ?

     
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  • Currently Being Moderated
    Nov 24, 2009 4:06 PM   in reply to deejjjaaaa

    I have no idea if this issue came up ever here. I myself have practically nothing to do with Pentax raw files; I implemented the support of a few models in Rawnalyze, but that's it.

     

    This attitude of Adobe we know it better what is useful and what is not comes up time and again. For example the masked area is removed from Nikon D90 and D300 files as well; although the pixel values of the image are black level corrected already, still that data should not be removed. The fact, that one doesn't know any usefulnes of that data is not the same that there can be no use of it.

     

    Gabor

     
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  • Currently Being Moderated
    Nov 24, 2009 7:24 PM   in reply to Sam Doran

    I'm in this boat too, converted a bunch of files with the dirty 5.5, and the original raw files were trashed by accident. If it was possible, I want to unconvert and reconvert my DNG's. I think I want to do this with all my DNGs (but that would cause me to lose my edits so I'll live with what I can unless they come up with a way to carry the edits across)

     
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  • Currently Being Moderated
    Nov 24, 2009 8:17 PM   in reply to hungchi

    Well, you are not in an enviable position. You can not go back to CR2 from the DNG, and the DNG converter will not repair the incorrectly converted 7D DNG files; it helps only if you start out with the CR2.

     

    On the other hand, keeping the former adjustments would not be much help anyway. The color changes quite much (actually, the color reproduction with the preliminary version was horrendeous), and the "brightness" of the image too changes a lot with ISO 100 shots.

     

    Anyway, I guess you learn now, that saving/archiving the original raw file is a task to do immediately (maybe after deleting the crapy shots).

     

    How many 7D files do you have now in DNG only?

     
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  • Currently Being Moderated
    Nov 24, 2009 8:39 PM   in reply to Panoholic

    @Panoholic

    My files are ARW sony raw From a sony a850 24.6mp DSLR not the 7D, but it's the same unofficial dirty support issue...I have a few hundred to a few thousand in DNG only. I know I've lost the dynamic range metadata from the few I had it turned on for and the aspect ratio capture (it defaulted back to full frame)

    it's all been personal work and not client work ( I would have used sony's raw converter for client work) so not a real big loss

    I've learned a lot with getting the a850 that is pushing me to now keep the original raw files  and upgrade my system

     
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  • Currently Being Moderated
    Nov 24, 2009 9:12 PM   in reply to hungchi
    function(){return A.apply(null,[this].concat($A(arguments)))}

    My files are ARW sony raw From a sony a850 24.6mp DSLR not the 7D, but it's the same unofficial dirty support issue

     

    That must be a misunderstanding. The A850's sensor is the same as the A900, nothing new is there. I converted an A850 ARW file with both the 5.5 and 5.6 DNG converter and compared the result. There is a tiny difference in the color reproduction specification. I compared the images in ACR 4.6 (among others a color checker card), and I found a few differences, but only 1 RGB value in one color, i.e. you would not notice the difference.

     

    In other words, you don't need to worry about anything. The very shadows will be as blotchy as with the A900 (due to the noise reduction on the raw data even at ISO 100), no raw converter can help on that.

     

    Gabor

     
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  • Currently Being Moderated
    Nov 24, 2009 10:28 PM   in reply to Panoholic

    Gabor, you are right the chip is the same and the reproduction is mostly the same as the a900. The issue is a lack of support for features like aspect ration capture. There are some differences in the a900 and the a850 despite the cameras having the same chip

    There are also a few features like dynamic range optimization that doesn't work or function correctly (I don't recalling that the D-range feature ever worked correctly on any Sony camera)

     

    It's features like the d-Range+ adjustments that I use the sony raw converter for.

     
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