How can you write/convert Picasa's People tags to the EXIF data?

Question

I use Lightroom for my workflow, and I tag photos with people's names so that I can find them faster.

Since Lightroom doesn't have the "Faces" feature, I want to use Picasa's People feature for this purpose, but I don't want to work constantly with both of them. I'd rather use Picasa to tag the photos with the name tags every time I import new photos, and come back to Lightroom for the rest.

I couldn't find a way to make Picasa actually "tag" the photos (in the EXIF) with the people's names. Is there any plugin / script / ... that can make this happen?

Answer

Picasa stores faces information in the .picasa.ini files:

[test.jpg]
faces=rect64(1eb1929f885e),15441a598f9f1866
backuphash=29866

The id numbers can be found in the contacts.xml file which stores all the contacts of your pictures:

<contact id="15441a598f9f1866" 
  name="Test Test" 
  display="Test" 
  modified_time="2010-05-13T17:19:46+01:00" 
  sync_enabled="0"/>

Several programs can read these files and modify the EXIF accordingly. For instance:

• faceextract.pl ( command line perl script )
• AvPicFaceXMPTagger (GUI)

Check more discussion of this question.