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Question: how much disk space is consumed by AI Denoising an image in Lightroom Classic 14.4?

Forum|Forum|9 months ago
June 18, 2025
5 replies
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Now that running AI denoise in Lightroom Classic no longer creates a new DNG, I assume it has to be storing a large amount of data somewhere. Before I go crazy with denoise (the results are often amazing!) and consume many GB of storage in my Lightroom library files, I wanted to get an idea how much space this takes.

I have no way of measuring the library file size increase after a single operation, so I tried the same operation in Adobe Camera Raw (17.4) and found that denoising one 30.8MB Nikon D500 raw file created a new a 6.1MB .acr sidecar file. So it appears that, at least in this case, denoise created an additional file that is about 20% the size of the original file.

Does anyone know if Lightroom Classic does something similar? If it does, that means that running denoise on 5GB of raw files (only about 162 D500 files) will result in growing the library files by 1GB. This is better than a whole new DNG, but it isn't insignificant, and would be part of library storage, not raw file storage!

As an additional question, will subsequently turning off (unclicking) denoise on an image in LRC eventually free up that additional storage requirement?

I use a Mac but the question would apply the same on Windows

Thanks in advance for any insight!

Don

Correct answer Rob_Cullen

This quote is taken from the link to the Lightroom Queen's blog-

https://www.lightroomqueen.com/whats-new-in-lightroom-2025-06/

"when we tested them on a 24 MB raw file, applying Super Resolution created approximately 48 MB of extra data, while applying only Raw Details generated around 18 MB of extra data. Denoise had the lowest impact, creating only about 5 MB of extra data. In Lightroom Classic, the new pixel data is stored in the .lrcat-data file alongside the catalog. In Lightroom Desktop Cloud mode, it’s saved to the cloud database."

gg100

Participating Frequently

Same problem here, my caatalog for 133,000 images was 2.1 GB

I added about 500 images, all of which I used the DENOISE feature

My catalog went from 2.1GB to 8.4GB

while storage of an 8.4 GB catalog is not a big issue for me right now, back up / loading etc all slow down with a very large catalog

I was able to "Fix" the issue by;

1 exporting all 500 images

2 creating a new folder in LrC

3 Import the exported images from step 1 into a new folder

4 Delete and remove all the original images

5 optimize the cataloge

6 once lightroom restarted the catalog went back to the 2.1GB

Adobe needs to address this, as no other feature causes catalog bloat to this degree

DdeGannes

Community Expert

@gg100 , When this thread was started LrC was at v 14.4 since then it has upgraded to v 14.5.1.

What version of. LrC do you have installed on your computer (indicate the actual version number) ?

Regards, Denis: iMac 27” mid-2015, macOS 11.7.10 Big Sur; 2TB SSD, 24 GB Ram, GPU 2 GB; LrC 12.5,; Lr 6.5, PS 24.7,; ACR 15.5,; (also Laptop Win 11, ver 24H2, LrC 15.0.1, PS 27.0; ) Camera Oly OM-D E-M1.

gg100

Participating Frequently

Yes, this thread started at 14.4, as I believe that was when the new denoise feature was added

I am currently running 14.5.1 and have duplicated the problem with this version.

T

thomas5CED

Inspiring

Are the AI enhanced images stored in the catalog forever or are they like a preview that get cleaned up after a while?
I guess there would be no harm deleting them after a while other than the cost of recomputing them, since the source data still exists, so Lightroom should be able to re-compute them if needed.

I don't see why they should end up in the XMP, there should be an option do prevent that or just never happen at all.

C.Cella

Inspiring

@thomas5CED the Ai Mask, the Generative Remove, the Enhance are NOT stored in the catalog but in the lrcat-data in a .blob

LrC Catlaog only has a reference to them so they can be loaded, no need to recompute them.

If you delte Ai Masks, the Gen Removes, the Enahce then they will be deleted from the lrcat-data I believe upon quitting LrC as part of a background optimisation of the lrcat-data database.

If you still keep histry then they will not be deleted I believe as the steps will have references to them.

This I need to verify but I belve that any .blob is kept as long as there's a reference to it in the catalog.

You can of course delte them and then you not only will have photos that appears different, incomplete, but will have to waste spend time recomouting them.

Frankly worry not about the size of the lrcat-data

If you ahve to worry about something then is XMP size that will be problematic as storing Enahce data in XMP will make saving keywords, title, captions in the sidecar even 10x times slower.

P

Paul McMurrick

Participating Frequently

I dont agree that you can 'frankly not worry about the size of the lrcat-data. When you set backup destination for your catalog, it creates a zip file that, when expanded, contains the cat and the lrcat data. Hence, you cant ask Backblaze or dropbox to selectively back up one or the other. So, in the last two weeks since I first started using the AI denoise, and adaptive color profiles in earnest, my zip file has gone from about 2 GB to now 20 times that size file, and I have to wait for dropbox to shift about 40GB of data each time I back up. That is with one week of work. Imagine what this will be like in a year, particularly if you are using medium format files. It is a disaster in terms of data management. Have a look yourself in your catalog settings

ouiouiphoto

Known Participant

Deal all

Test with R7 raws

In the XMP we are supposed to find metadata including dev metadata. If you do a simple dev your XMP is around 10Ko. If you add masks, you have to save in the XMP the mask drawing. This can take place. But with a lot of masks, you are still under 1Mo. But if you use Denoise by AI your xmp goes to 5Mo or more. Why to save the denoise result in the XMP ? Why not to save instead that denoise AI why used with the slider value like it is done for exposition. In the XMP you don't save the exposition result but just that is was used and the value of the slider. Why Denoise is not the same ? If anyone have an idea. Just to know why. Because personally i don't use xmp at all

Kind regards

.Sheepdog trying to help Lightroom and Photoshop beginners

J

Jao vdL

Community Expert

Normally the denoise result is put in the catalog only. It only gets put as a copy in the xmp when you have automatic xmp writing turned on. This data has to reside somewhere. In previous versions of Lightroom, a separate dng file would get created with the denoise data. In the new version, the denoise data that allows you to charge the amount of denoising after the fact is stored in the metadata in the catalog. Denoising this way unavoidably adds some megabytes that have to be somewhere.

ouiouiphoto

Known Participant

Hello @Jao vdL . When you add exposition or contrast, you don't have the exposition or contrast result in the XMP. You only have the slider value. So I wonder why this is different with Denoise. You could imagine just to have if it is applied and the slider value as for exposition And when you import in a new catalog the file with the XMP, as for the exposition, Lightroom will redo the denoise.

.Sheepdog trying to help Lightroom and Photoshop beginners

R

robert36972564

Known Participant

Oh no! 😮😣

Please, Adobe, store all of this data only with the RAW files!

My Lightroom Catalog already is about 1 TB in size, mostly due to (mostly standard sized, not 1:1) previews but also several GB for the data/db files of the catalog. The LR Catalog is stored on a high-end 2 TB SSD (just upgraded from 1 TB a few weeks ago), to make culling etc. fast enough.

I really DO NOT want to fill up this pricy storage with data that I or LR won't need the next few months/years after first processing. This kind of data belongs to archive/cold storage!

I mean I could manually move that .lrcat-data folder to my HDD and place a symbolic link or junction, so that LR doesn't notice. But this presumably would heavily slow down the AI processing while editing.

@Adobe Simply store all such data next to the RAW files.

My current projects (RAW + XMP files) are stored on another SSD for speedy edits and imports. The AI Denoise data would be there too. When I'm done, they get moved to external HDDs (consuming about 14 TB currently), not blocking scarce SSD space anymore.

I was so happy to hear about non-destructive AI denoise without monstrous DNG-files anymore. But now they broke the batch workflows (see other community threads) and clutter storage space... I will skip the 14.4 update. 😑

JohanElzenga

Community Expert

Oh no! 😮😣

Please, Adobe, store all of this data only with the RAW files!

My Lightroom Catalog already is about 1 TB in size, mostly due to (mostly standard sized, not 1:1) previews but also several GB for the data/db files of the catalog. The LR Catalog is stored on a high-end 2 TB SSD (just upgraded from 1 TB a few weeks ago), to make culling etc. fast enough.

By @robert36972564

That is never going to happen. If you use Lightroom Classic, then you'll have to accept that Lightroom Classic is a database application, so all the edits are stored in the database and its supporting files. Storing the enhance data only with the images would make the database not contain all the edits.

As you said, your issue of having a 1TB catalog folder is not caused by enhance data and will not be exaggerated by enhance data (unless you would enhance every single image). It is caused by your previews (and smart previews if you have these too). The Catalog Settings contain more options to limit the size of previews. Previously you could only set how soon 1:1 previews would be discarded, but now you can specify a maximum size for the previews cache. Lightroom will delete standard sized previews of the images you did not view recently, starting with the oldest.

And if you have smart previews, then ask yourself if you really need them. Many people seem to think these are some kind of 'previews on steriods' or 'intelligent previews', that somehow improve what they see on screen. They're not. The name is misleading, because they have nothing to do with previews. They are proxies for your raw images, so you can edit even when the external disk is offline. If you never do that, then you don't need smart previews.

-- Johan W. Elzenga

C.Cella

Inspiring

But it does seem to be quite a bit more efficient than when it still stored a separate DNG file. Example: A ~30MB DNG from my A7IV denoised would be around 80MB. Now, with the lr-data solution, it is only a very small increase (as observed by Lightroom Queen).

The thing is, the 5MB is not telling the whole story. I did the following test: Take a folder from my LR-Catalog and convert it into a standalone catalog. I then opened that new catalog and created some AI denoised images from a subset of the images in the catalog. I noticed around 150 MB were created in lr-data. I then proceeded to create denoise for all images in the catalog: lr-data remained at 150MB... 🤯

Finally, I am synching my catalogs between Laptop and Desktop. I skip the synching of the lr preview-Folder on purpose, because that contains many small files which makes synching slow. Now, if I open the Catalog on the Laptop, it will ask me to "update the AI settings" on the images that I had previously AI denoised on my Desktop PC. I assumed that would mean that now my laptop would have to redo the whole AI-Denoising, but it was quite quick... So what it really did was just "recreate the previews from the denoise data stored in lr-data".

So a summary of what I've found out so far:

lr-data seems to store ai settings and enhanced info (e.g. denoise)
- The size increase of lr-data is kind of hard to track; sometimes it increases, sometimes it doesn't? --> Would be greate if Adobe could clarify
lr preview-folder seems to store the previews with applied AI denoise
- If you move the catalog with lr-data but without lr preview, LR will ask you to "update" the AI settings and this runs much faster than if you actually let AI Denoise run on that computer, since the "Denoise"-info seems to be lr-data

Did another small test, this time with 3 11~15MB DNG files from my GX80:

No image denoised
aiDenoiseTest.lrcat-data 0,03

1 image denoised
aiDenoiseTest.lrcat-data 1,75

2 images denoised
aiDenoiseTest.lrcat-data 4,56

3 images denoised
aiDenoiseTest.lrcat-data 6,09

Notice how the size increase is not always the same. The first image denoise was around 1,72 MB; the second 2,81 MB, the third only 1,53 MB. It all seems to be stored in the 00008.log (or so) file in lrcat-data.

Really curious how this actually works! Hope Adobe will chime in.

@daehxxiD

The blob and the acr. are nearly identical if you compare them.
Substantially is the same data

ACR has no database so saves AI images, bitmaps and so on into the .acr sidecar.
LrC saves AI images, bitmaps and so on into the lrcat-data (blob) AND inefficiently in the XMP, essentially bloating them.

(Well actually is still ACR that does the saving for LrC but the choice of format is LrC)

Rob_Cullen

Correct answer

Community Expert

This quote is taken from the link to the Lightroom Queen's blog-

https://www.lightroomqueen.com/whats-new-in-lightroom-2025-06/

"when we tested them on a 24 MB raw file, applying Super Resolution created approximately 48 MB of extra data, while applying only Raw Details generated around 18 MB of extra data. Denoise had the lowest impact, creating only about 5 MB of extra data. In Lightroom Classic, the new pixel data is stored in the .lrcat-data file alongside the catalog. In Lightroom Desktop Cloud mode, it’s saved to the cloud database."

Regards. My System: Windows-11, Lightroom-Classic 15.1.1, Photoshop 27.3.1, ACR 18.1.1, Lightroom 9.0, Lr-iOS 10.4.0, Bridge 16.0.2 .

D

DonHAuthor

Known Participant

Thank Rob, that's exactly what I was trying to figure out. I suspect the ratio of denoise data to raw file size will vary by raw file type, degree and type of raw compression , etc.

Don

C.Cella

Inspiring

A SuperRes Image is way more than 2x the size of the RAW from which it orginates.

RAW file is 36,2Mb
XMP no edits = 44Kb
XMP with SuperRes = 162,2MB

ACR saves Enhance data into a more efficient format the .acr

.acr with SuperRes = 129,7MB

The big problem is that LrC is inefficient at writing into XMP even on SSD.
This is how long it took to save the SuerRes data into the XMP form the moment of clicking "Save" to the moment the XMP is finally written.

LrC should adopt the .acr format to store this data which is both faster to read and write ( XMP requires all data be encoded as text) and is lighter than XMP.

For DNGs the SuperRes is saved in the file, in the inner-sidecar, so DNGs become massive.

Still not as big as with the baked SuperRes.

Looking at the .lrcat-data doens't fully reveal the impact of this big data for our storage capacity and workflows.

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