Can't delete XMP:Description

[Archive]

[Originally posted by johnrellis on 2008-11-01 01:57:36-07]

I've got some photos from which exiftool (7.51) can't delete XMP:Description.  For example:

Code:

C:\>exiftool -xmp:description description-bug.jpg
Description                     :

C:\>exiftool -xmp:description= description-bug.jpg
    0 image files updated
    1 image files unchanged

When I dump the XMP using -b, I see the following, which I think is legal but looks suspicous:

Code:

 <dc:description>
   <rdf:Alt/>
  </dc:description>

Is this an exiftool bug or ill-formed XMP?

[Archive]

[Originally posted by bogdan on 2008-11-01 06:29:14-07]

Hi,

As far I can see, there's nothing to delete, because xmp:description doesn't contain any value.

Why don't you try to define some value for description:

Code:

exiftool -xmp:description=MyDescription no-bug.jpg

..then you'll get something like:

Code:

 <dc:description>
   <rdf:Alt>
    <rdf:li xml:lang='x-default'>MyDescription</rdf:li>
   </rdf:Alt>
  </dc:description>

Bogdan

[Archive]

[Originally posted by exiftool on 2008-11-01 14:50:39-07]

I agree with Bogdan, there is nothing to delete.
But I ran some tests and exiftool does not properly
handle an empty list like this when adding new values.
What software generated the empty list in the first place?
(It wasn't exiftool.)

I will add the ability to deal with empty lists like this when
adding new items to an empty list, but I'm not sure I'll be
able to come up with a solution for the "nothing to do"
when attempting to delete an item that doesn't exist.

- Phil

[Archive]

[Originally posted by johnrellis on 2008-11-01 16:56:55-07]

Thanks very much for your prompt help.

Now that you point out that 'exiftool' doesn't add values correctly in this case, I can see that clearly in the XMP.  Originally, I tried to add an XMP:Description value but was getting very confused by the various tools in play.

The files were produced by an Epson 4490 scanner (which doesn't add XMP) and then cataloged by Adobe Photoshop Elements, probably versions 5 and 6.  There's this line in the XMP:

Code:

Adobe XMP Core 4.1.3-c001 49.282696, Mon Apr 02 2007 21:16:10

Semantically, 'exiftool' exposes the difference between tags that are found in the file with empty values and tags that aren't found in the file.   When the tag is present with an empty value, 'exiftool' prints it out; when the tag isn't present, 'exiftool' prints nothing.  In general, 'exiftool' lets you delete tags from files, so it was mildly surprising I couldn't do it here.

 

I'm reconciling the metadata in the Elements catalog with the files' metadata (made fairly messy by Elements).   Because the 'exiftool' output is different in the two cases, I was trying to make the reconciliation cleaner by deleting tags with empty values.   But it's one more minor issue that's straightforward to work around.

 

Thanks again.