Downgrading preview quality and size

[ATEriksen]

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

[ATEriksen]

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]

About the previews.lrdata file:

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

[ATEriksen]

I'm sad to say you have the wrong information. This is from Adobe Support and their developers.

So this is really a case where Adobe needs to fix the function so people don't waste time ruining their work and having to redo a lot of tagging. 

[GoldingD]

You could consider copying the catalog, then testings out on the copy. Naturally have good complete backups.

[ATEriksen]

TLDR: If I get time I'll try it on my wifes PC, but I kind of trust Adobe on this one. 

I did ask Adobe spesifically about these issues and also asking them if facial recognition used standard previews to register faces. Then I asked if moving or deleting preview was going to unlink /remove face  recognition data, along with other questions on this issue.

The support guy made me wait about 10 minute while he was checking dev documentation and asking his closest seniors, but found nothing about how this impacted facial recognition data. The support guy had to put me on wait some hours until devs and other seniors could answer him because this was an issue that he couldn't even find answer to and wanted to solve asap. 

The reply you see is when he asked his devs/seniors, and they confirmed standard previews is used / linked to facial recognition since deleting or moving the file would unlink/remove the face data, so I'm not tempted to waste time trying to overprove this to see if Support is wrong or lying. I'm also afraid that I'm going to hamper the facial recognition in some other way when changing catalogue or messing up my Cloud Sync while at it. This is also a production system, so I really don't have time or patience to mess around then having to fix everything again.

There is something to be said about faces located at a X,Y in 3072px long edge preview vs 2048px preview when changing the resolution. Most likely it wont be in the same place anyway, so the better option is to make sure application resize preview and keep the box/link over the face when preview changes. 

It is not like I'm out of space right now or have dire needs. I can survive until they fix this issue within resonable time so that we don't not needed to whack around catalogue system files - potentially breaking anything. I also see so many posts on this issue that it kind of needs to be resolved properly soon. The function has been there for about two decades, with many posts on similar support cases, where only solution is to delete or move previews file. It's not become any better for anyone after all this time, so I will make sure this change for the better so we all can have a better experience with previews 😀 

Best regards,
Aleksander

[ATEriksen]

@Rikk Flohr: PhotograpFlo

Adobe told me pr telephone they were going to implement a fix for this generate lower res preview issue.

Do you know or see if there is any progress or is it just submitted as a suggestion still?

Thanks.

Aleksander 

[JohanElzenga]

I'm sad to say you have the wrong information. This is from Adobe Support and their developers.

So this is really a case where Adobe needs to fix the function so people don't waste time ruining their work and having to redo a lot of tagging. 

By @ATEriksen

It is sad to see how much nonsense Adobe support sometimes tells people. Previews are just jpeg images, that show you how the image will look when the non-destructive editing is applied. The previews.lrdata does not contain face recognition data! These data are stored in the catalog file.

[ATEriksen]

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

[JohanElzenga]

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'.

[JohanElzenga]

Come to think of it, I believe I may understand what caused the confusion at support and why they gave you an incorrect answer. If you go to the face recognition view, then you'll see the idividual faces. These are obviously previews, like all image views are previews. So if you delete the previews.lrdata package, then you will almost certainly delete those face previews too. That is most likely what they meant. However, those are only the previews (the small jpegs) themselves, not the face recognition data (like the assigned people keywords, and the position of each recognized face). As said, these data are stored in the catalog. So when you start Lightroom again and it starts rebuilding the previews.lrdata package, the face previews will be rebuilt as well.