Obetz, my experience with ratings is that DxO prefers its own metadata over the XMP, once its own data is created. Even if the XMP has a later modification date.
Besides the tons of technical data (aperture, speed, focal length, ISO, lens, GPS coordinates etc.) generated in the camera:
Creator aka author aka By-line
Copyright aka rights
Description aka Caption
Keywords
Location (Country, City, Sublocation)
and much more.
Such data can be stored in Exif, IIM or XMP sections, all of them either embedded in the raw image file or in a sidecar, IOW same information can be stored in several places.
A raw developer like Photolab can act as “creator” or “changer” in MWG speak with far-reaching consequences.
PL will keep all informations from embedded data (Exif/Maker notes) for output image.
About XMP, there are several parts in the content.
if the “preserve metadata in XMP sidecar for RAW images” option is checked, PL will keep all informations from XMP sidecar
if this option is unchecked from preferences, output image will have only few information from XMP sidecar (like rating, orientation)
About rating in PL and output image: the priority is set as following: PL > XMP > EXIF. By default, rating from XMP/Exif will be imported in PL (yellow star), once we change the rating in PL, the highest prio will be taken for PL and output image will have the rating from PL.
About keywords, PL won’t display keyword/description/comment from Exif part. Currently ONLY keywords from XMP sidecar will be imported and displayed in PL.
XMP writing (inside PL) part has not yet been implemented, but may be in the near future.
So with an example from obetz, only “an ugly beast” keyword will be used in PL.
So please dont hesitate to share us your thinking on this topic.
My experience has been that once PL writes any data to its database, the XMP sidecar is never looked into for that data again (unless you delete the database).
That behavior is unfortunate as many photographers use other apps that update info in XMP and play well together.
thanks for your detailed answer especially about the “preserve metadata in XMP sidecar for RAW images” option, htran.
We need to be cautious about the wording: “XMP” is used to name the sidecar but also for an information section inside the image file or sidecar. Sorry that I was not that clear in my OP.
I think I remember that XMP data embedded in the raw file is also read by DxO Photolab if there is no XMP sidecar, IOW: If XMP-dc:Description embedded in the raw file contains “a nice dog”, and there is no XMP sidecar, the exported jpeg will have “a nice dog” in it’s XMP section.
Will an IPTC IIM section be read and exported by Photolab?
Generally, I think it is a good idea that DxO Photolab gives the sidecar data higher priority than the metadata embedded in the image file. If an application creates a sidecar, this is very likely the most recent container.
Perhaps DxO can explicitly point out in the Photolab documents that this is intentional and will remain unchanged.
I do not work with sidecars - only embedded data. I can confirm if you embedd “a nice dog” into your file (raw, jpg…) and run that file through DPL then “a nice dog” will be in the exported file.
Dear obetz,
Yes, i confirm that output image will have the same keywords from input one even keywords come from embedded XMP or from seperate XMP sidecar.
HT