[Digikam-users] IPTC handling and limits

Gilles Caulier caulier.gilles at gmail.com
Wed Sep 12 20:24:07 BST 2007

2007/9/12, Thomas Hummel <hummel at pasteur.fr>:
> On Wed, Sep 12, 2007 at 12:43:12PM -0400, Gilles Caulier wrote:
> >   . this field is 64 byte wide and can only store full ASCII characters
> >
> >
> > yes
> >
> But I read somewhere that keyword is a multi-value field, so the 64B limit
> is only for one keyword but I can have unlimited number of keyword. Is that
> true ?

yes, in theory. For JPEG, the IPTC  section is limited to 64Kb. for PNG and
TIFF, there is no limit.

To be clear, if in digikam I assign, for a picture the following flags :
> people/family/thomas
> people/family/laurence
> animals/cats/timi
> ...
> can I have any number of those saved in IPTC keywords as long as each of
> them (such as people/family/thomas) is less then 64B long ?


> Note : XMP support is under developpement and will be available for next
> > release 0.10.0 (KDE4). XMP remplace IPTC-IIM.
> >
> > All these limits will disapears : UTF-8, no size restriction, etc.
> > kipi-plugin to edit metadata will be updated of course.
> Quite interesting indeed.
> Will there be some way to migrate existing IPTC flags or should I wait
> (since I
> 'm only begining to use tagging (so it may not be too late for me) ?

all tags are stored in digiKam DB. when all will be ready in 0.10, just use
the sync pictures<->DB tools  to update all in your images. Of course the
future right options to sync XMP must be enable (XMP config panel not yet

> yes, it's truncated automaticly by Exiv2 library.
> Ok, what about accents (I think I put some in tag names before knowing it
> wasn't supported)  : are they skipped ?

There is a patch to support UTF-8 with IPTC-IIM, but i'm not satisfied by it
because IPTC workflow is broken with others photo management software. IPTC
and char encoding is infernal and badly normalized. This is why Adobe have
created a new format (XMP) to remplace it.

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