Aperture exported IPTC4XMP sidecars not readable by Adobe or PhotoMecanic

I'm going to be watching this one too as I was under the impression that exporting xmp sidecars at this point was as easy as pie. I've not had the reason to test this as I don't use alt software to process/edit my RAW files but... Having the option to migrate, if the need should arise, is important to me and having my metadata go along with my files is extremely important.

Curious about this one.

P.s. Did you see this recent blog post? It has info regarding the xmp sidecars but it sounds like you are already doing this correctly:

http://photofocus.com/2010/11/11/converting-from-lightroom-to-aperture/

Just to narrow it down a bit: What metadata fields in particular are missing? or is it all of them? What version of Photo Mechanic are you using? What version of DNG converter are you using? And what settings are you using in DNG converter?

David:

There have been some real problems with the way in which Aperture 3 writes metadata (see http://www.controlledvocabulary.com/imagedatabases/aperture3.html for details), however in previous versions the XMP sidecar was readable in other applications. The snip of the XMP sidecar file you provided above is the same as other samples I checked from earlier versions.

It could be that there are issues in how the rest of the XMP file is written, but there are other potential pitfalls.

You mention them not being recognized by DNG convertor. Have you viewed the images (and their sidecars) in Bridge or Lightroom (assuming you have one or the other)?

As for Photo Mechanic, it's important to realize that how you have the preference set up can definitely affect how metadata is read. See the Photo Metadata tutorial I authored, specifically this page ( http://www.photometadata.org/META-Tutorials-Photo-Mechanic-Setting-Metadata-Pref erences), to make sure that you have set up PM correctly for an XMP sidecar workflow.

If you'd like, I'd be glad to take a look at one of your CR2 files and companion XMP files that you've exported from Aperture. Contact me offlist (I think you can DM me via Twitter) and I can set up a Dropbox shared folder where you can upload the files.

David

David:

Thanks for sharing the file (CR2 and XMP) that you were having problems with. This made it possible to track down the issue, though by no means easy. It took me a couple of hours, and the answer was not where I expected to find it. I thought I'd share the process here, so that others might have an idea of how to to trouble-shoot something like this in the future.

When I attempted to view the IPTC Info dialogue in Photo Mechanic for your problem file, I would get the following error message "Error reading caption from photo" message.

When I open in Bridge for CS3, I could see an entry in the Creator field of "David Gordon +44 [rest of your phone number]" Ditto in for Bridge for CS4 and CS5.

When processed the file via ACR that field persisted. However, from our follow up correspondence off list, you identified that as information entered in the camera. Indeed, when I search the XMP, there is no similar entry, so this indeed appears to be the case.

When I viewed the contents of the XMP file in a text editor, I could see many other metadata fields, so there certainly was a problem.

I took the XMP file from an earlier export that I knew worked, and renamed it to match your CR2 file. The metadata for that file displayed without any problems in Photo Mechanic.

I then tried taking the same known exported XMP file, opened it in a text editor and then "cut" the mid section from the BJK05091.XMP file and pasted it into the other. I then renamed so it would be the same as the original CR2. However, this was still not recognized by Photo Mechanic (same error as above). When viewed in Bridge, I got the same result.

I then spent much too much time, inspected the XMP/XML/RDF code, line by line, expecting to find an error in that, but couldn't find any deviations from my example (which contained all the the metadata fields in Aperture... with the Aperture label entered as the value).

That meant I either missed something, or it was some data value in the XMP itself.

So I started swapping in segments from the "good" XMP file into your problem XMP file, and changing the file name of the CR2 to match so that I could then try too open the file in Photo Mechanic.

Finally, in the last segment I found the answer to your mystery....

and the answer is.... &

No, really, the culprit was a couple of Ampersands, those "&" symbols that had been placed into the Usage Rights field before you exported the XMP sidecar.

While the ampersands I had found and replaced with a simple "and" were in the Usage Rights field, they would prevent you from seeing the metadata for the file; regardless of which field they are placed in.

To figure out why that might make a difference, I tried entering an Ampersand "&" into the Caption(Description) field in Photo Mechanic and Bridge. When I inspected the XMP sidecar in a text editor, I found my answer. These applications were using the "&" code!

In HTML the ampersand is assumed to begin an "entity" reference. (see http://htmlhelp.com/reference/html40/entities/ if you really want to know about these).

So it appears that the Apple engineers either made the assumption that no-one would ever enter an ampersand into a metadata field (rookie mistake), or they forgot to write an escape routine into the Aperture software for those times when someone did use an ampersand (and presumably other entity references).

I tried entering a tilde "~" into the XMP from a text editor and that worked just fine. However, greater than ">" and less than "<"&" and other symbols until after you test them out.

Hope that makes your morning!

David

I just wanted to offer my thanks for this very helpful sleuthing - awesome work!