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LR3 JPEG/DNG Metadata Confusion

Aug 7, 2011 11:56 AM

Hi,

I'm a little confused about XMP data and the LR3 catalog itself.

 

First, I understand that DNG files can have embedded keywords and other metadata -- and 95% of my files are CR2 files that I bring into LR3 as DNGs and keep them as DNGs.  So I am NOT using raw files with sidecar files.

 

But where I'm confused is the "automatically write changes into XMP" LR3 catalog option and how it relates to JPEG files.

 

I was of the understanding that if I make changes in the develop module (eg. contrast)  to a JPEG file (not a DNG), then these changes will NOT be saved to the original JPEG file, but will be "recorded" in the LR3 catalog.

 

But now If I allow LR3 to "automatically write changes into XMP"  -- will this WRITE these develop module changes (e.g. the contrast change)  to the original JPEG?  Or does the "automatically write changes into XMP" only refer to the keywords and other metadata in a JPEG file?

 

Thanks for any help in clearing this up,

R

 
Replies
  • Currently Being Moderated
    Aug 7, 2011 12:56 PM   in reply to Reg2233

    LR by default writes all your work with imported files to the Catalog. If checked "Auto write changes to XMP" will also create a side car for raw files, for DNG, TIFF, JPEG etc the XMP data will be stored within the file itself.

     
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  • Andrew Rodney
    1,388 posts
    Apr 16, 2009
    Currently Being Moderated
    Aug 7, 2011 12:55 PM   in reply to Reg2233

    Reg2233 wrote:

     

     

    But now If I allow LR3 to "automatically write changes into XMP"  -- will this WRITE these develop module changes (e.g. the contrast change)  to the original JPEG? 

    You only write the instructions, not the rendering with Auto write XMP (or command/control S in a manual fashion). So if you open such a document in say Photoshop, you will NOT see the color any differently than before you wrote those metadata edits. You have to actually render out an iteration (a new JPG in this case) to see the edits applied in the new document.

     
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  • Currently Being Moderated
    Aug 7, 2011 1:07 PM   in reply to Reg2233

    R,

     

    In  both cases (DNG and JPEG), LR - if instructed so by "automatically write ..." or Ctrl-S - writes metadata into the so called XMP section of the appropriate files, and does not alter the image data itself.

     

    In the case of a DNG, this written data includes metadata such as keywords, title, caption etc. as well as develop settings.

     

    In the case of a JPEG, this includes metadata such as keywords, title, caption etc., and develop settings only if "Include Develop settings in metadata inside JPEG, TIFF, and PSD files" is checked in the catalog settings.

     

    The develop settings written into the XMP section can only be seen if you open the image with a tool that recognizes and interpets this data, i.e. open in PS/PSE via ACR or a re-import into LR.

     

    Beat

     
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  • Currently Being Moderated
    Aug 7, 2011 1:08 PM   in reply to Andrew Rodney

    You would see the effect of the XMP data in the JPG if your PS is new enough and you have PS set to use ACR on the way in for JPG files that either have settings or always, but you see those changes because PS has called on ACR to render them, not because they are in rendered into the file, already.

     
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  • Currently Being Moderated
    Aug 7, 2011 1:37 PM   in reply to Andrew Rodney

    thedigitaldog wrote:

     

    So if you open such a document in say Photoshop, you will NOT see the color any differently than before you wrote those metadata edits. You have to actually render out an iteration (a new JPG in this case) to see the edits applied in the new document.

     

    Actually, if you write the xmp adjustments into a JPEG, I'm pretty sure Bridge will see them (if you have the ACR Prefs set to open JPEGs with settings) and you can always open the JPEG using Camera Raw which deffinately will see the adjustments if the ACR prefs are set to use Camera Raw to open JPEGs with settings.

     
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  • Andrew Rodney
    1,388 posts
    Apr 16, 2009
    Currently Being Moderated
    Aug 7, 2011 4:06 PM   in reply to Jeff Schewe

    Yes of course ACR will see the adjustments and provide you a ‘correct’ preview but Photoshop will not. I might have to try Bridge (I generally don’t use it at all).

     
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  • Currently Being Moderated
    Aug 7, 2011 5:06 PM   in reply to Reg2233

    Reg2233 wrote:

     

    But now if I opened this keyword, added contrast-adjusted JPEG in another program,  only "XMP-aware" programs would allow me to see these keywords and contrast changes.  Is this a correct assessment?

     

    Yeah, pretty much...but the key is how you've set the Camera Raw prefs...

     
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  • Currently Being Moderated
    Aug 7, 2011 5:21 PM   in reply to Reg2233

    The IMAGE DATA is not affected when you write XMP settings to it.  That is what is being referred to by non-destructive...you're not changing the image data of the JPG, just adding extra things to the headers that are not part of the image.

     
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