Replacing an image in place with a new better scan, while retaining edits, orientation, crops, keywords, and collections?

[neilhunt]

Lightroom Version

LR Classic 9.1

Operating System

1. macOS 10.15 Catalina

I have an unusual problem: I scanned a few thousand slides, and imported them into Lightroom Classic, fixed orientations, created some collections, did some edits, etc.
I also retained the RAW scanner output - which isn't actually useful in Lightroom - it's scanner-specific, and LR doesn't appear to know about it.

For a small number (100s) of dark slides, the scanner default Color Temperature setting is weak. I can virtually rescan the scanner-RAW files with a different setting, and produce better images, which look much better in Lightroom, and edit better as well.

If I remove the originals images and re-import, I lose all the collections, keywords, and develop settings.
If I replace the file in place, Lightroom is fussy about rereading the image file, but if I can get it to "take" the new data, the result is what I'm looking for.

Question: How do I get Lightroom to forget all it's previews and cached versions of the original file, and look at the new pixels instead?
I have tried removing the original image file, then invoking Library/Previews/Discard 1:1 Previews and Library/Previews/Discard Smart Previews, but it seems to retain a version of the original pixels, and I can even Develop the retained file. I know if I wait a few days, I will get a white missing image rectangle, but I can't seem to get LRCC to drop the cached version on request - is it a "standard preview" that is stuck? Is there a way to delete it?

Observation: There is apparently a "bug" (at least, anomalous behavior) where Rotate 90 CW or Rotate 90 CCW state is recorded in the image file metadata and not in the LRCC database metadata. In replacing the image file, the orientation is lost. Cropping rectangles are retained, and other metadata, but not the orientation! Wierd.
The fix for this is, prior to replacing the image file, to copy orientation from the original image file with something like this:
/usr/local/bin/exiftool -tagsfromfile "OLD/ImageFile.tif" -Orientation "NEW/ImageFile.tiff"
Now the orientation is retained just fine.

 

[Johan Elzenga]

I have tried removing the original image file, then invoking Library/Previews/Discard 1:1 Previews and Library/Previews/Discard Smart Previews, but it seems to retain a version of the original pixels, and I can even Develop the retained file.

If the previews in the Library don't update, then use 'Library - Previews - Build Standard-sized Previews'. If the preview in the Develop module does not update, then try Preferences - Performance - Camera Raw Cache - Click the 'Purge Cache' button.

 

[johnbeardy]

I replace the files in place, and then do a Save Metadata to Files. This saves all LR's keywording and other metadata back into the new file, and you can then do a Metadata > Read Metadata safely which will update the non-IPTC stuff. The menu commands to delete existing previews and build 1:1 then work normally, though I accept this area often appears flaky.

 

[Johan Elzenga]

Just by coincidence, I did replace a scanned image with a new one just a few hours ago and did indeed get the problem that the develop module preview did not update and showed the old version. I used the same method as you.

 

[johnbeardy]

Yes, I think the Metadata > Read Metadata is an important step. Going to 1:1 view in Develop (triggering the Loading message) appears to do the same thing.