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A
ATEriksen
Known Participant
November 14, 2023
Question

Downgrading preview quality and size

  • November 14, 2023
  • 1 reply
  • 1126 views

Hello,


Mods:
I consider this problem a bug since previews settings changed and no regeneration of previews happen on previously built previews, even if it's asked for manually in the menus.

Problem:
Standard previews was set too high before facial recognition work was done on half million images. Nothing happens in Lightroom process tree if I lower quality and pixels then regenerate "standard preview" and select all. Program probably assume I don't need to rebuild the older standard previews since they exist, even if settings changed. Or... it should work but it doesn't.

 

I have MANY files so I really don't want to go through and delete Master_Catalog-v13 Previews.lrdata file, rebuild ALL previews, and possiblly losing all facial recognition data while at it. Adobe Support couldn't promise i lost the facial recognition data or not when deleting this file. 

 

What outcome I wish for:

Set lower standard preview quality and pixel dimentions so that I can save some space on my half million older images, then do smart previews or something else etc on newer more current files. I could also use embedded or sidecard images on my older images, but I can't see any options to sleect using embedded or sidecard after the fact. 

Previous Catalog settings:
Standard preview size: (Auto) 3072px
Quality: High
Delete 1:1: Every 30 days

Current Catalog settings:
Standard preview size: 2048px
Quality: Middle
Delete 1:1: Every 30 days

Simply upgrading disk because "storage is cheap" isn't a solution I'm going for,  it is also an inefficient way to solvie things in the long run. Image data accumulates a lot, and old images doesn't need to be full size in their previews after some years.. I think Adobe and application should be more ECO friendly and save environment, users money and users frustration when they can. This means either regenerate new standard previews if settings has changed since last time, especially if user request it - OR - at least ask if user like to rebuild the standard previews with the new settings.

Best regards,

Aleksander

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    1 reply

    A
    ATEriksenAuthor
    Known Participant
    November 14, 2023

    I have to add..

     

    Adobe couldn't confirm if moving Master_Catalog-v13 Previews.lrdata would detach keyword (name of face) from image data (face location in file), so I'm not eager to try moving it either.. I'm also having second thouhgts about moving/deleting preview file and regenerate lower resolution previews, because if face was at a certain point in a 4096px document, it would certainly not be in the same location at 2048px if they used pixel location as identifier. I'm guessing facial recognition is linked to the preview in some way.

     

    Weird that this regenerate standard preview doesn't work on previously generated ones with new settings, the option has been there since first version of Lightroom AFAIK.

     

    Anyway. I hope Adobe fixes this, because I can't think this is how it was designed, it has to be a bug..

     

    Regards,
    Aleksander

      GoldingD
      GoldingD
      Legend
      November 14, 2023

      About the previews.lrdata file:

      https://phototacopodcast.com/is-it-safe-to-delete-lightroom-previews-lrdata/

       

      JohanElzenga
      Community Expert
      JohanElzengaCommunity Expert
      Community Expert
      December 14, 2023

      Hi Johan,

       

      Well, the previews are jpegs for sure baked in to the .lrpreviews file and smart previews in its own file. I asked what happens if you delete that previews data, if I only deleted the previews or if I also unlinked/deleted the datapoints for facial recognition. There was a lot back and forward on this case, they even set up a phonecall between Norway (me) and USA (Adobe) to make sure we all was on the same page. They promised to talk with seniors and engineers about this, and this was their reply. 

       

      I can only guess there will be a unlinking of the datapoints and preview resulting in lost faces in catalog, or... You actually delete both preview and the datapoints. 

       

      I don't even want to try it, because I just finished adding some hundred thousands of faces in my catalog. Don't want to risk losing data, not even risk unlinking face from name-keyword. 

       

      Where do you get that datapoints are stored in the catalog file, do you have a source on this? I'm just curious.

       

      Aleksander


      Just try it yourself with a small test catalog. You don't need to use your main catalog. Create a new catalog, import a few people images, activate face recognition, delete the previews file* of this test catalog and then see what happens. Deleting the previews package is done quite often by people to keep the size of this package manageable. I have never heard of any report that this would delete face recognition data. I don't use face recognition myself, but I can assure you that it does not detach keywords from images.

       

      * For your info: the previews 'file' and the smart previews 'file' aren't really files at all. They are 'packages' on your Macintosh (and folders on Windows). A package is a folder that looks and behaves like a file. You can open it as a folder by right-clicking on it and then choosing 'Show Package Contents'.

       

      -- Johan W. Elzenga
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