Photos show banding when viewed in the cloud, but not in Lightroom Classic

Thanks, Todd.

here is the link: https://feedback.photoshop.com/conversations/lightroom-web/photos-show-banding-when-viewed-in-the-cloud-but-not-in-lightroom-classic/605cd28bc7571a4888e303c4

DJ I use lossy DNG file format quite a bit to reduce the file size of large HDR and Panorama DNG files. 99% of these lossy DNG files look identical to the original raw file. In general heavily underexposed image files (-greater than 2.0 EV) suffer from lossy DNG file format artifacting. Your original file is not underexposed and all settings changes I tried failed eliminate the banding in the smart preview uploaded to the Cloud. You can create the same smart preview file type for examination using the LrC Export module with the below settings.

I suggest reporting this in the Photoshop Family forum. https://feedback.photoshop.com/

I reported an issue with lossy DNG file format concerning Spot Removal two years ago with no fix to date. It's still worthwhile filing a new report for this banding example. Place a link back here to the report and we can add further comments there to help get Adobe's attention.

https://feedback.photoshop.com/conversations/lightroom-classic/lightroomcamera-raw-converting-raw-files-to-lossy-dng-sometimes-results-in-purplecast-previews-in-the-library-module/5f5f45ee4b561a3d4268d267?commentId=5f5f48f54b561a3d4245f414

This suggests that the smart previews synced with LR Cloud is sharing the same inferior preview-building code with Library previews.

Again, I'm surprised by this, I thought the point was to show the image with roughly the same quality (although fewer pixels) as in LrC. And I can't recall others complaining about this.

"I shouldn't have to use Lightroom (cloudy) to obtain results. And I shouldn't have to export and re-import and then upload to the cloud to see the photo without banding, as I thought this was an actual feature of Lightroom Classic ... Although you didn't say this, it sounds like a bug that should be reported to Adobe."

I agree.Though given Adobe's explicitly stated policy of no more improvements to LR Classic sync after LR Cloud was released, I wonder if they would ever prioritize a fix.

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Also, when I import the sample DNG into my LR Classic with Build Previews: Standard, I see the banding in Library Loupe with Fit zoom.  If I force a 1:1 preview to be built by zooming to 100% or doing Library > Previews > Build 1:1 Previews, the banding goes away.  This suggests that the smart previews synced with LR Cloud is sharing the same inferior preview-building code with Library previews.

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The first step is to understand why this is happening, then from that we can determine how to avoid the issue.

Your sample file confirms my hypothesis.   The banding is a result of the lossy 8-bit smart preview that LR Classic syncs to LR Cloud.  Uploading the DNG directly to LR Cloud avoids the banding.  Exporting the DNG from LR Classic as a quality-75 JPEG shows no banding, either at the original width of 6048 or the reduced width of 2560, which is why you don't see banding when published to Flickr.

It appears that LR is using an inferior algorithm for building the smart previews from raws.  I don't know how to get to the smart previews synced with LR Classic, but you can access those built by Library > Previews >  Build Smart Previews (they're stored in the catalog folder in *Smart Previews.lrdata). They're a little smaller than those synced to LR Cloud (2268 wide versus 2560).  If you build a smart preview in LR Classic for the sample DNG and then open it in Photoshop, you can see the banding.  But if you export a quality-75 JPEG at width 2268, there is no banding visible.  The JPEG is 1.6 MB, while the smart preview is 1.5 MB.

Some workarounds:

- Export the raw back into the catalog as a full-size quality-75 or -85 JPEG and sync the JPEG.

- Upload the photo directly to LR Web (http://lightroom.adobe.com) rather than syncing it from LR Classic.

- Maybe Todd can suggest alternative editing steps that will avoid the problem.

You can see the three versions of files in LR Web here:

https://adobe.ly/31kp1w6 

(the full-size quality-75 JPEG synced from LR Classic, the DNG synced from LR classic, the DNG directly uploaded to LR Web.)

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LrC Smart Previews synced to the cloud are 2560 px long edge lossy DNG files. Banding issues are usually due to specific settings in the Develop module, which may be correctable to prevent banding. The best way to determine this is to Export the raw file with your settings to DNG file format, upload it to Dropbox or other file sharing site and put the share link in a reply here. I'll take a look at it and provide editing suggestions.

What export module settings are you using for the LrC JPEG export file? Try JPEG 75 Quality, Adobe RGB, Resize to Fit Long Edge 2560 and Output Sharpening Screen Standard. This should be similar to the Smart Preview synced to the Cloud.

Jeffrey Friedl's Flickr plugin may be converting the image to 16bit PNG file format, which is a Flickr supported file format.

My hypothesis: You synced the image from LRC to LR Cloudy, and LRC always syncs raws as smart previews. Since the smart preview only has 8 bits per channel, you get the possibility of banding.  If you upload the image directly into LR Cloudy from your hard drive rather than via LRC syncing, I think you could get a preview in LR Cloudy without banding.

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