You don't need any plugin for this.

3) install + activate the LocalFiles Editor plugin.

4) open [Administration > Plugins > LocalFiles Editor > Local config] and paste:

<?php
$conf['use_iptc'] = true;

$conf['use_iptc_mapping'] = array(
  'keywords'        => '2#025',
  );
?>

And then perform a metadata synchronization on your photo (from the photo administration page for example)

ADMST wrote:

Thanks a lot.
Is there also a way to copy keywords into tags?
As I find keywords will not show up.

Just give a try to my suggestion :-) it does transform IPTC keywords into Piwigo tags.

rbr28 wrote:

Is there something similar for exif and/or xmp?

Sorry but no. EXIF are not designed to contain such information. XMP are not supported by Piwigo core 2.1 (but they are with the [extension by grum] Advanced Metadata, see my [Forum, post 114385 by plg in topic 16154] XMP tags)