Preview files have multiplied

Forum|Forum|1 year ago
September 4, 2024
2 replies
1266 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.

JohanElzenga

Community Expert

Hi Ian, I've read your reply three times, but it does not tally with what LRC 13.5 has actually done in my test. To reiterate, the NEF files imported into my test catalog were fullsize from my Nikon Z8 camera so had dimensions of 8256x5504. They were not cropped either in camera or in LRC (the xmps that they had in my main catalog were left behind). On importing LRC automatically created three new preview files for each image - 2064, 1032, and 320 (according to their filenames). These seem to be correct sizes of 1/4, 1/8, and 1/32 of the actual file size (8256). Why there was no 1/16 is presumably known only by the LRC team. When the 1:1 previews were made these were 4128 and 8256, the 1/2 and fullsize previews. On deletion of 1:1s, only the fullsize 8256 was deleted leaving the 1/2 size (4128) behind.

What seems to be misleading is the default catalog prefs entry of 'Auto (2560)'. Wondering about that for a while, I suddenly realised that it was the monitor size (Eizo CG 2730) - 2560x1440. The actual previews are not directly related to the monitor size but to the file size (8256).

I hope this clears things up?

Bob Frost

To me, it does not. Yes, the preview (auto) size is related to the monitor, not to the image. Change your monitor settings, and you'll see that this changes 'Auto (xxxx)' too. That makes sense, because you want to be able to see the image in loupe view on your monitor, and you want to be able to do that in full screen mode. That means you need an image that is 2560 pixels wide; the width setting of the monitor. So why Lightroom does not create that 2560 pixels preview is not clear to me.

-- Johan W. Elzenga

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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