5 Replies Latest reply on Jan 21, 2015 2:23 PM by areohbee

    How to trigger LR to discard standard previews?

    Cornelia-I Level 4

      This is NOT about smart previews, but Library-module previews. It is neither about 1:1 previews, but standard previews.

       

      Situation: I use an external SSD as "external catalog disk", with my LR catalog and the previews on it, in order to plug it to 2 different computers which I use alternatively.

      Due to a badly considered synch-folder import I ended up with unwanted effects and way too many images and previews, so I decided to go back to the last good catalog backup.

      So in theory I should have had 100GB of excess previews from the discarded catalog version, no longer needed for the restored catalog version.

      How do I trigger LR to throw them away?

      I tried to trigger the build of standard previews of folders, which contain now much less images than before, hoping that this would get rid of them. To my astonishment LR said it had to rebuild almost all of the previews for the chosen folders. Why - they should have been there already? Usually, when a backup-catalog version is restored as current (same name, same storage location), the previews are recognized?

      After this finished a night later, I still have the same size of the catalog previews folder!

       

      Any ideas?

       

      Before you suggest that I delete all previews and let LR rebuild them from scratch: we are talking of a catalog of 2,2GB size, 150'000 images, and 190 GB of previews (plus 146 GB of smart previews, although they are not my current concern). This will take almost a week to rebuild... so I'd prefer something more straight forward.

       

      Thanks, Cornelia

        • 1. Re: How to trigger LR to discard standard previews?
          areohbee Level 5

          The short answer: you can't trigger Lr to discard standard previews.

           

          What you can do if you're short on space for them (other than the obvious: "get a bigger drive"):

          * reduce standard preview size - in fact, if standards are too big, then 1:1 previews won't be deleted when you delete them (when Lr deletes them) - long story.

          * reduce standard preview quality - even "low" quality is good quality, but certainly switch to medium if on high now, at a minimum.

          * move previews to a different drive and replace previews folder with a link to the relocated folder.

           

          PS - PreviewExporter does have a feature to discard selected standard previews, but it only works on a copy of your previews database, and so isn't very convenient.

           

          Rob

          • 2. Re: How to trigger LR to discard standard previews?
            Cornelia-I Level 4

            Hi Rob,

            Thanks for your quick answer!

            Do I understand correctly that LR would never get rid of previews, unless I delete an image from the catalog within LR and have it open afterwards for sufficient time that it no longer is prepared for the undo?

             

            If the images are already missing from the catalog (thanks to an older backup restore), would your PreviewExporter Plugin find them?

             

            Cornelia

            • 3. Re: How to trigger LR to discard standard previews?
              areohbee Level 5

              Hi Cornelia - long time..

              Cornelia-I wrote:

               

              Do I understand correctly that LR would never get rid of previews, unless I delete an image from the catalog

              Yes, you do understand correctly - the only way to get Lr to delete standard previews is to remove photo from catalog (not sure about the undo part).

               

              Cornelia-I wrote:

               

              If the images are already missing from the catalog (thanks to an older backup restore), would your PreviewExporter Plugin find them?

              Well, if the photos have been removed from the catalog, then PreviewExporter won't find corresponding previews (it only finds previews of selected photos). (if photos are in catalog but missing from disk, then it will find them). Interesting idea though - a feature to remove all extraneous previews - 'twould be easy enough to do, just hasn't been done, yet.

               

              Rob

              • 4. Re: How to trigger LR to discard standard previews?
                Cornelia-I Level 4

                HI Rob,

                 

                the little delay about throwing away a preview after deleting an image from the catalog I quote from Victoria Bampton's Missing FAQs. Quite useful to wait an average undo-period.

                 

                I would be happy to find a plugin from you that would sort out this issue about superfluous remnant previews... Anyhow the logic about creating and assigning standard previews keeps me puzzled, as my non-scientific observations always seem to have them "never" without update need.

                So a house-cleaning plugin, which would purge superfluous remnants and check for updateness of existing standard previews would be useful.

                It might happen more often after all that one imports a bunch, maybe even as virtual copies, and decides afterwards that one best abandons this and returns to one's last good backup catalog, which befits fewer previews.

                 

                Thanks for considering,

                Cornelia

                • 5. Re: How to trigger LR to discard standard previews?
                  areohbee Level 5

                  Cornelia-I wrote:

                   

                  the little delay about throwing away a preview after deleting an image from the catalog I quote from Victoria Bampton's Missing FAQs. Quite useful to wait an average undo-period.

                  I guess I'll have to give you/V the benefit of the doubt for now.. - thanks.

                   

                  Cornelia-I wrote:

                   

                  Anyhow the logic about creating and assigning standard previews keeps me puzzled, as my non-scientific observations always seem to have them "never" without update need.

                  I've read that a half-dozen times now . If I understand, it breaks down thusly:

                  * You sometimes have previews for photos which no longer exist in the catalog (e.g. due to dragging a backup catalog file into the catalog folder).

                  * Even when previews exist for a photo, they're often out-of-date, and therefore not much fun (since Lr re-builds them when it goes to use them anyway).

                   

                  Adobe provided a method in Lr5 for plugins to update previews, but it doesn't work well enough, and so I'm not using it, except in a few limited/experimental contexts.. But I could find a way to remove extraneous previews, and also to select photos whose previews are out of date, at which point the "build standard previews" function could be invoked, either manually or programmatically (via plugin) using keyboard stuffing. Let me give that some thought..

                   

                  Rob