Problems synchronizing metadata with Lightroom

[skippix]

Sigh...

I have been using Lightroom since v2 to process and catalog my photos. When I finish working with a group of photos, I save the metadata to file, injecting all the Lightroom updates into my files. Until about 4 months ago, I shot exclusively in jpg; now I'm shooting in Raw + jpg. The Lightroom metadata save does not update the Raw file, but instead creates a sidecar xmp file.

While I have been using ExifTool for a number or years, until about a year ago I used it only for date-shifting. I've been developing a Windows GUI in Delphi (based on Bogdan Hrastnik's interface), but had to put it aside last summer. Everything had been coming along nicely.

I decided to pick it up again yesterday so I could start dealing with my Raw files. And now things are coming off the rails.

The basic idea is that I would use my interface for captioning and cataloging and Lightroom for the image manipulation (for clarity, this means adjustments made in Lightroom's Develop module, such as to exposure, white balance, etc.). Exiftool does what it's supposed to do, updating the image file.
Even though Lightroom reads the file correctly. However, if I edit the IPTC data and save the metadata, it creates an xmp file rather than injecting the data into the Raw file.

Here are my problems:
1) I'm not sure of the tags to use to correctly read the xmp file created by Lightroom
2) If I make additional edits to the IPTC using Exiftool, Lightroom ignores them when I use Lightroom's read metadata function

The challenge is synchronizing the image files (both the Raw and the sidecar jpg), the Lightroom xmp, and the Lightroom data. I need both the IPTC data and the image manipulation, and it seems to make the most sense for the image file to contain the IPTC data and the xmp file to contain matching IPTC data and the manipulation data. This would allow for another program (such as Photoshop) to be able to work with the file without having to start from scratch. I would also want to inject the xmp data into the jpg sidecar so that it is also in sync.

Where to begin?

TIA,
Skip

[Phil Harvey]

Hi Skip,

1) I'm not sure of the tags to use to correctly read the xmp file created by Lightroom

I don't understand.  Why can't you read it "correctly"?

2) If I make additional edits to the IPTC using Exiftool, Lightroom ignores them when I use Lightroom's read metadata function

Do you really mean what ExifTool calls IPTC (the IIM format)?  Or are you talking about the IPTCCore metadata in XMP?  I'm hoping you're not using IPTC/IIM.

- Phil

[skippix]

Thanks for getting me out of my fog, Phil!

Of course, Exiftool reads the XMP files perfectly. I noobishly had not tried it before posting, and apologize. (I had only looked at a file in notepad and saw tags that I did not recognize (like "rdf"), and that gave me my Chicken Little moment).

And yes, I was using IPTC/IIM and not XMP- related tags. I have a better understanding now as to what Lightroom is doing and what I need to be doing. The relationship between Lightroom and metadata simply highlights the critical value of your tool, Phil. Lightroom behaves like a precocious teenager, assuming it is infallible and immortal, that it's internal data and the sidecar files will forever and always be in the world with the actual image file. It's a terrible risk to take, not to immediately inject the xmp data back into the Raw files. I'm also having to learn which tags to ignore in jpgs created by the Lightroom export (it appears to use both the IPTC/IIM and XMP- related tags).

Anyways, thanks for your direction, as well as your incredible tool!

Skip