Preview files have multiplied

Forum|Forum|1 year ago
September 4, 2024
2 replies
1272 views

Why are there now hundreds of thousands more files in my preview folder? Some (but not all?) preview files (.lrprev) have associated files that seem to be different sizes of previews. They haven't been there in the past. What has changed?

Bob Frost

Windows

This topic has been closed for replies.

JohanElzenga

Community Expert

Lightroom Classic 13.5 changed how previews are stored. In the past, a preview file contained a number of different size previews in one single file. Maybe these are now saved separately. Anyway, do not bother about it. This is not something the user needs to be concerned about.

-- Johan W. Elzenga

Ian Lyons

Community Expert

> Maybe these are now saved separately.

Yes, they're now saved as separate files. The file format is JPEG, albeit with no extension.

Ian Lyons

Community Expert

Not quite finished! To investigate the 1:1 previews in the new preview sytem of LRC 13.5 I created a new catalog and imported 50 nefs (about 45Mp each). LRC created new previews according to its defaults (auto - 2560 and medium quality), and looking at the new previews I have three for each image - 320, 1032, and 2064 in size.I then created 1:1 previews which added 4128 and 8256 in size. Then deleting the 1:1 previews only deleted the largest size that it had created - 8256 - and left the 4128 size that was created by the build 1:1 preview command. Interesting. No .lrprev files at all, but three .lrfprev files for the three faces in those images.

So to sum up, using 'build 1:1 previews' creates two larger sizes of the new format previews, but deleting them only deletes the largest.

Happy Lightrooming! Bob Frost

When files are imported with standard-sized previews, then maximum preview size will reflect the size set in Catalog Settings. There will also be 2 or 3 other files that are ½, ¼ and 1/8 of the largest preview. However, when 1:1 previews are built the largest sized preview will either be the cropped size or actual size with other smaller previews being ½, ¼, etc of the largest.

When the 1:1 previews are discarded, the largest preview for a cropped file will now be half of the full sized cropped files dimensions, etc.

So, from above we can see that the standard-sized preview as set in catalog setting is only applicable until 1:1 previews are built, then the cropped dimensions take over.

I've attached a screenshot that may help make above a tad clearer. The previews groups with red boundary are cropped files.

dj_paige

Legend

Assuming you are discussing Lightroom Classic (which you didn't really say):

You may have changed an option at Import that increases the number and size of previews. For example, at Import you had selected "Minimal Previews" and then later you selected "1:1 Previews".

But LrC uses these preveiws to speed up your workflow. If you get rid of some (or all) of them, things slow down in the Library Module whenever LrC has to generate a preview. It's a tradeoff ... more disk space for faster workflow; or less disk space and slower workflow.

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