I’m about switching form Lightroom to Darktable. In my LR catalogue there are about 80,000 photos, mainly DNGs with embedded RAWs from different Olympus DSLR-cameras. My LR version is 5.x on Mac OS X 10.7.5 and my DT version is 3.4.1 on Debian 11 with X11.
To make DT able to take as much LR photographic preparations as possible I have to extract the XMP files out of the DNGs. I do this with exiftool. Otherwise no adaptions are recognized. With the XMPs color markers are recognized, hierarchical keywords. (There is another exiftool command necessary to avoid the same keyword doubled.)
The results of the import in terms of optical appearance are some times pretty good some times very bad. Especially crops are not recognized although this is claimed at the DT website for a long time. Worse, the image appears to be black only. See here:
Furthermore the stars are not taken from the XMP file to DT. I assume this comes from the feature to rate the importing image. If I could deactivate this it will be ok I think.
You may have better luck with the xmp and the original raw file. I don’t think this feature ever worked super well, its hard because adobe changes things and people generally do this once then don’t look at it again.
No, I tested it. Because I have the RAWs embedded in the DNGs I can extract them and work with them. Nothing better. (And it would be impractical to extract 80,000 RAWs. )
He was saying to use the xmp file created by Lightroom itself, not the xmp ad created by exiftool. Because that will probably shifted data around so darktable doesn’t get it anymore.
So make Lightroom write the xmp files (there is a chance this only works for original raw files ).
First I would use dt 3.6.1 if possible. For the crop I agree it should always be good (I’m the author of the Lr to dt import). But I have seen some issues on some cases when used with rotation. Anyway, I have switched since a very long time now so no more experience with this.
For the stars, color labes and keywords I had never had issues which is the most important as anyway you need to get back to each image imported before printing or exporting it as there is zero chance for the imported history to be “correct”.
FILE can be a single XMP file or more or a directory as far as I remember. This way only the hierarchical keywords are imported. Also for original RAWs.
If you’re sure they’re all dupplicated you can mass-remove the extra tags from darktable’s database by eliminating them once all images are imported (not ‘remove from image’, but ‘delete tag’). This won’t remove them from the sidecars until you open the corresponding image or force the xmp to be written, though.
Of course, as this would be a pretty destructive operation: test and backup before!
Further tests show that cropping is ignored during import for all DNG files and for all RAW files extracted from DNGs where they were embedded. Only “Original-RAWs“ can be imported with crops. Sigh! I have 5,500 croped images!
Maybe comparing XMP files of LR with the ones extracted from DNG with exiftool shows some solution.
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