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Eruditass
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DNG: Embed medium JPG preview corrupted?

May 25, 2012 7:47 AM

Tags: #dng #lr4 #corrupt_file

When I select embed medium JPEG, the preview image is corrupted (folded over itself parallel to the long edge) when I view the preview in other programs like irfanview.

 

Two examples:

 

http://dl.dropbox.com/u/16299441/Photography/20120219-IMGP4799-full.dn g

http://dl.dropbox.com/u/16299441/Photography/20120219-IMGP4799-medium. dng

 

http://dl.dropbox.com/u/16299441/Photography/20110706-IMGP2589-full.dn g

http://dl.dropbox.com/u/16299441/Photography/20110706-IMGP2589-medium. dng

 

jpeg screenshots:

http://i.minus.com/iqXtqJHjY0nzU.jpg

http://i.minus.com/iAXjDDNVIfi8C.JPG

 
Replies
  • Andrew Rodney
    1,386 posts
    Apr 16, 2009
    Currently Being Moderated
    May 25, 2012 10:49 AM   in reply to Eruditass

    Jargulator wrote:

     

    When I select embed medium JPEG, the preview image is corrupted (folded over itself parallel to the long edge) when I view the preview in other programs like irfanview.

     

    iffanview isn’t up to the latest version (spec) of DNG we have in LR4 nor are many other such applications. The data is fine, it isn’t previewing the new spec for JPEG previews correctly. Tell them to update their software. Your data however is fine.

     
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    May 25, 2012 11:32 AM   in reply to Andrew Rodney

    dcraw (and tools based on it) hasn't yet been updated to read DNG images with embedded Fast Load Data.

     
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  • Currently Being Moderated
    May 25, 2012 11:47 AM   in reply to Andrew Rodney

    Andrew Rodney wrote:


    Tell them to update their software.

    And how they supposed to do this, if the new DNG specification is not released yet?

     
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  • Andrew Rodney
    1,386 posts
    Apr 16, 2009
    Currently Being Moderated
    May 25, 2012 11:51 AM   in reply to cppasm

    cppasm wrote:

     

    Andrew Rodney wrote:


    Tell them to update their software.

    And how they supposed to do this, if the new DNG specification is not released yet?

     

    They contact Adobe and say something to the effect “Please provide the latest SDK so we can update our software”.

     
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    May 25, 2012 11:59 AM   in reply to Andrew Rodney

    Actually, no update is needed.  Nothing has changed about the spec or SDK.  All that is really needed is a bug fix in the software to avoid getting tripped up by the optional preview image that is embedded in the DNG.  (Notice that you can open this file in old versions of ACR which don't even support the new spec.)

     
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  • Andrew Rodney
    1,386 posts
    Apr 16, 2009
    Currently Being Moderated
    May 25, 2012 12:34 PM   in reply to MadManChan2000

    MadManChan2000 wrote:

     

    Actually, no update is needed.  Nothing has changed about the spec or SDK.  All that is really needed is a bug fix in the software to avoid getting tripped up by the optional preview image that is embedded in the DNG.  (Notice that you can open this file in old versions of ACR which don't even support the new spec.)


    Even better! When I had the same issue while playing around with Raw Photo Processor, the author made it sound like they needed to update something in reference to the JPEG. But they were aware of this and like others, hopefully they will fix the issue.

     
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    May 25, 2012 2:43 PM   in reply to MadManChan2000

    MadManChan2000 wrote:

     

    Actually, no update is needed.  Nothing has changed about the spec or SDK.

    Does this means that DNG specification update with description of newly added FastLoadData will not be released?

    I understand that FastLoadData is only one more optional preview image in a TIFF structure and if software is written properly, it can just ignore it if it is unable to work with it correctly.

    I just wanted to ask will FastLoadData structure and compression scheme be described in the DNG spec someday when Adobe thinks it's time to do this, or it just will became new optional proprietary Adobe extension to DNG?

     
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    May 25, 2012 2:54 PM   in reply to cppasm

    cppasm wrote:

     

    I just wanted to ask will FastLoadData structure and compression scheme be described in the DNG spec someday when Adobe thinks it's time to do this, or it just will became new optional proprietary Adobe extension to DNG?

     

    Did you read what Eric wrote? The fast load data should NOT cause any problems as long as the DNG reader does not have a bug that trips it up on the fast load data being there (which it shouldn't). Whether or not the fast load data gets into the DNG 1.4 spec which is due soon'ish or not I can't say (Eric could) but the other stuff in DNG 1.4 will be documented such as Lossy DNG and Proxy DNG (which is what I think they refer to as downsampled lossy DNG). The fast load data is, as far as I know, only used by ACR and LR and sort of supersedes the ACR Cache.

     
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    May 26, 2012 3:15 AM   in reply to Jeff Schewe

    Jeff Schewe wrote:

     

    Did you read what Eric wrote? The fast load data should NOT cause any problems as long as the DNG reader does not have a bug that trips it up on the fast load data being there (which it shouldn't).

    And did you read what I wrote?

    I understand that Fast Load Data could just be ignored by application, it's not causing any problems if there is no bug.

    But DNG is an open standard, which means EVERYTHING about it should be described in the specification and freely available to the public.

    If something is not - it's nothing more than proprietary extension.

    So I'm just asking whether Fast Load Data will be described in the upcoming new DNG specification or not.

     

    Jeff Schewe wrote:

     

    The fast load data is, as far as I know, only used by ACR and LR and sort of supersedes the ACR Cache.

    But it potentially could be used by other applications if format of data and compression scheme will be documented.

     
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  • Currently Being Moderated
    May 29, 2012 6:29 AM   in reply to cppasm

    Two things:

     

    1.  Yes, the Fast Load Data info will be described in the spec ...

     

    In the meantime, with the exception of the compression (which is simply JPEG), it already is described in the current published spec.  Everything else that is needed to read & process the data was described previously in the DNG 1.2 specification.

     

    2.  That said, even though the DNG format is documented & public, that does not mean that all data contained in a DNG image is documented & public.  For example, private MakerNotes in a DNG are usually undocumented and proprietary, by design.  Similarly, embedded XMP metadata is readable by everyone, but the specific meaning of the fields will depend on the software.

     
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