Lightroom Classic: Library artifacts and banding

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When I import my pics, standard previews and smart previews are generated. I develop my pics just fine. But when I go back to the Library module, with some pictures only, the sky is full of artefacts (Fit screen). If I zoom in in 1:1 or higher, after recalculation, those artefacts desapear. But when I go back to Fit screen I see them again. I don't see them in Develop Module.

If I build again 1:1 previews, it does solve the problem. But it's not persistant.

And the worse part is when the collection is synced, I see on LR web the pic with the artefacts.

How could I avoid this ? How do I correct the situation in LR Web without having to resync everything ?

All the pics are coming from the same camera in raw and there is no crazy edit in the sky.

I did export a set of files as per your settings with :


  • sRGB
  • AdobeRGB 1998
  • Prophoto RGB
 All pics are fully clean pics.

I downloaded directly from LR web : artefacts as I see it in LR web

I deleted the preview file and the sync.lrdata. I rebuild the preview and started the sync again. Still the same problem, notting changed. 



Thanks for your help
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ChrisB63

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  • frustrated

Posted 1 week ago

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Rikk Flohr, Official Rep

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Any chance you can share a screenshot or two showing the artifacts? 
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Rikk Flohr, Official Rep

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I really need to see what your screen looks like. 
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ChrisB63

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ChrisB63

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a print screen from LR web
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ChrisB63

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I would like to say again the banding is not visible in LR 1:1 or higher but only in fit screen and in LR web. Export pics are fully clean 
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ChrisB63

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Rikk Flohr, Official Rep

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And a screenprint of Library module showing the banding?
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ChrisB63

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ChrisB63

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This from the desktop (MacOS) LR Classic
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Ed Wolpov

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Rikk, this has been happening forever! There are lots of posts complaining that one has to zoom to 1:1 in order to eliminate what looks like severe jpeg blockiness. For me, this seems to happen only when in the Library module, and it's inconsistent in that it only occurs randomly. It's most noticeable in the sky or where there's smooth tones. Once the 1:1 zoom is recalculated, the artifacts are gone... for a while, but they randomly return at a later time. 
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Todd Shaner, Champion

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The artifacts observed in the LR Classic Web synced smart previews are due to use of lossy DNG file format. You can test this by exporting images that exhibit artifacts in the Web album using the below LR Classic Export module settings. To be honest after looking through my 35,000+ images catalog for files with similar sky area I could only find two that exhibit artifacts when synced to the Web with LR Classic.

https://forums.adobe.com/message/5297705#5297705



To determine the cause (and a possible correction) I suggest exporting a few files that exhibit the artifacts to full-size DNG file format as shown below. The DNG file will contain your LR Develop settings to determine if that has some bearing on the issue. Please post them to a file sharing site and place the share links in a reply here.

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Simon Chen, Principal Computer Scientist

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You'll see this type of artifact when the standard preview is generated based on Smart Previews or at higher pyramid levels (it explains when you zoom to 1:1 the artifact went away).

Try increase your preferred standard preview size from the Catalog Settings>File Handling>Preview Size>Standard Preview Size. If it is setting to Auto, the size is determined by the largest dimension of your attached monitor. The artifact could also be amplified by the type of extreme image adjustment he applied to the image when the standard previews are not generated from the full resolution negatives.
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ChrisB63

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I understand what you saying. But in this case there is no special extreme edit.
If it was the case, there would be still visible in 1:1 or higher. It would be visible as well when I export with the publish service as a jpeg and it's not the case at all with any pictures. 

Any how this is a big problem for :
- simply view the pics in fit screen
- kills the LR web
- kills the possibility of sharing with LR web

In the catalog settings the preview are set to Auto and preview to high quality.
By downgrading one or both of them it will degrade the viewing quality.

what is the fix ?

Thank you all for your help 
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Try increase your preferred standard preview size from the Catalog Settings>File Handling>Preview Size>Standard Preview Size.
Simon, does the Preview Size setting affect the file that is synced to the Web, which is where the artifacts are also visible?
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Simon Chen, Principal Computer Scientist

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Hi Todd, No. The standard preview size only affect the previews generated for the library.
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Simon Chen, Principal Computer Scientist

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But in this case there is no special extreme edit. If it was the case, there would be still visible in 1:1 or higher. It would be visible as well when I export with the publish service as a jpeg and it's not the case at all with any pictures. 
That would make sense because in these cases (1:1 and publish and export), the rendering always start with the full resolution negative (to ensure the highest quality but render slower). This kind of artifact is mostly occurring when the rendering is based on the Smart Previews (like the LrWeb case) or camera raw negative cache (in essence, Smart Preview likes)

Any how this is a big problem for :
- simply view the pics in fit screen
- kills the LR web
- kills the possibility of sharing with LR web
These are the cases where the renditions are rendered from the Smart Preview or the Camera Raw (negative) Cache.

There is no easy fix without performance implications. If image quality is your top priority, during import, set the preview option to generate 1:1 preview. Or do it 1-off for affected photos by quickly zooming into 1:1 to force generation of 1:1 preview for that photo.
(Edited)
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ChrisB63

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This kind of artifact is mostly occurring when the rendering is based on the Smart Previews (like the LrWeb case) or camera raw negative cache (in essence, Smart Preview likes)
So to avoid this I deleted the file Smart Preview. right ?
No how do I force a resync with LR web ?


I'm quite unhappy about this situation as smart preview has been created to improve performance (not only) and now you are saying in order to be able to use Portfolio / Gallery etc I should not be using smart preview
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Todd Shaner, Champion

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So to avoid this I deleted the file Smart Preview. right ?
See this post for what I believe Simon is referring to:

Develop module preview differs from Library + Exported JPGs

If using Smart Previews with  "Use Smart Previews instead of Originals for image editing" selected in LR Preferences set OR the original file is offline you are looking at and working with a lossy DNG file. Uncheck that setting and make sure the original file is present AND create 1:1 Previews. This will "fix" the artifacts issue as observed in the Library module, but not the Sync to Web images since they are lossy DNGs and nothing you can do to change that. What you can do with those specific images that exhibit artifacts in a Web album is to instead create and sync rendered JPEG files for those specific image files. See my reply below outlining that workflow.
(Edited)
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ChrisB63

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Thanks Todd, I will try this
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ChrisB63

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If I understand you well I could “solve” the problem by :
- not using smart preview
- disabling the cash by setting it to minimum ?
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Todd Shaner, Champion

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As Simon Chen mentioned, "If image quality is your top priority, during import, set the preview option to generate 1:1 preview. Or do it 1-off for affected photos by quickly zooming into 1:1 to force generation of 1:1 preview for that photo."
- disabling the cash by setting it to minimum ?
I assume you mean the camera raw cache,. It is only used in the Develop module so not a source of this issue. Setting to a low value is only going to cause performance issues in the Develop module. If anything increase the camera raw cache size to 20-50 GB.

Also as Simon Chen mentions, "No. The standard preview size only affect the previews generated for the library."

As mentioned the smart preview file is a lossy DNG file with fixed size of 2560 pixels long edge and NO user adjustable settings. If you're seeing artifacts in a LR Classic Web synced image file there's no much you can do.
What does appear  to work is to export the raw file to JPEG file format using the below settings and then sync the JPEG file to the Web. With your Speloncato-7501178.NEF and the XMP file settings applied I see no artifacts in the sky. It's not an ideal solution and I can't even explain why it works, but it does. As long as you have no intentions on applying Web edits to the file there shouldn't be any issues. A side benefit is that the synced JPEG file with Screen Standard Export Sharpening applied appears sharper than the synced raw file.

(Edited)
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Simon Chen, Principal Computer Scientist

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@Todd One correction, the Smart Preview is a lossy DNG file with fixed size of 2560 pixels on the long edge.
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Todd Shaner, Champion

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Thanks Simon, correction noted and changed in my post. That's what I had always thought in the past, but Web downloaded JPEGs are always 2048 px long edge. Is that an arbitrary download size determined to be more useful due to social media posting size limits (i.e. Facebook is 2048 long edge maximum)?
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Simon Chen, Principal Computer Scientist

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2048 px is the JPEG render size. The 2560px for Smart Preview is to provide some slack for possible cropping during develop.
(Edited)