Re: [gthumb-list] Date fields in gThumb 3 comments

[Paolo Bacchilega <paolo bacchilega libero it>]

Il 13/10/2013 10:57, Rennie deGraaf ha scritto:
> Hello
>
> Like gThumb 2, gThumb 3 stores comment data both in an XML comment file
> and in IPTC tags.  In gThumb 2, the IPTC date was treated as
> authoritative: if the comment file was missing or the date differed, the
> comment file date would be replaced with the IPTC one.
>
> This seems to have changed in gThumb 3. If the comment file is missing,
> the date is re-created from the EXIF date, rather than the IPTC date.
> Further, the default behaviour in the comment/metadata dialog is to
> replace the date with the EXIF date, even if an IPTC date and comment
> date are already set.

the date is read from the following fields, in decreasing priority order:

Exif::Photo::DateTimeOriginal
Xmp::exif::DateTimeOriginal
Exif::Photo::DateTimeDigitized
Xmp::exif::DateTimeDigitized
Xmp::xmp::CreateDate
Xmp::photoshop::DateCreated

I don't know why the IPTC date is not present, maybe it was just overlooked.

> This new behaviour is a problem for me.  I keep my camera clock in UTC
> so that I don't need to worry about changing the camera clock when I
> travel.  However, I want the display date on my photos to reflect the
> local time zone where they were taken, so I change the time in the
> comment.  With the gThumb 3 behaviour, I need to manually correct the
> time every time I edit a photo's comment, rather than just editing it
> the first time and trusting gThumb to leave it as I left it.
>
> Is there any particular reason for the new behaviour?  If not, any
> chance that it could be reverted to the old gThumb behaviour?

gThumb 3 has two possible behaviours, that you can change in the 
preferences dialog:

1) keep the embedded metadata in sync with the XML metadata: in this
   case after reading the embedded metadata the XML metadata is
   updated if it differs; when writing the metadata both embedded and
   XML metadata are updated.

2) embedded metadata is not updated: in this case after reading the
   embedded metadata:
   *) if there isn't a XML comment file, the XML metadata
      is updated with the embedded metadata.
   *) if a XML comment file exists, the embedded metadata is ignored.

- Paolo