[Digikam-users] Comments in png files

[Gilles Caulier]

2007/11/5, Paweł Marciniak <pave at o2.pl>:
>
> Thank you Gilles for replying!
>
> Gilles Caulier wrote:
> > Exiv2 do not support yet PNG metadata for writting. Patch still
> uncomplete
> > on my computer.
> > [...]
> > yes, Caption, date, rating, and tags are store in digiKam database.
>
> I see. Is there a way (it may even involve some hacking) to retrieve the
> captions from db and embed them in jpeg files? Otherwise it's A LOT of
> rewriting for me :(


But al is always done by digiKam. Are you sure to have set on right right
options in Metadata setup dialog page ?


>> When converting manually with convert, no error is raised, but when I try
>
> >> to
> >> view the converted image in digiKam, no metadata is shown at all.
> >
> > Exif and iptc ??? Impossible (:=))). All my photo collection are in PNG
> > (taken originally from JPEG or RAW), and metadata still present of
> course.
> >
> > Witch camera you use ? Can you send me a JPEG file taken with your
> camera
> > to test. How are you converted your JPEG files to PNG ? Using Camera
> > interface during download ?
>
> Yes, there's nothing after opening the photo in digiKam (display(1),
> however, sees exif metadata in the jpeg, but not iptc). I found out that
> the digiKam console says:
>
> 8<-------------------------------------
> Warning: IPTC dataset Iptc.Application2.Preview has invalid size 67904;
> skipped.


This is the problem. Preview (an embeded and reduced JPEG image) is set by
digiKam in IPTC to speed up preview loading (F4).

problem is than preview IPTC can be larger than 64Kb (see iptc/iim paper)
and a jpeg section (used to embeded iptc in jpeg file) is limited to 64Kb.
Ther eis no size limitattion with PNG (or TIFF)

I have already fixed the problem in digiKam core, Exiv2 but not yet in
kipi-plugins. Of course i will do it.

Note : it's originally a problem of imagemagick wich trunk whole iptc if
size is over 64 kb during PNG=>JPEG (or TIFF=>JPEG)

Please make a file in bugzilla, in kipi-plugins/BatchProcess component.
Thanks in advance

Gilles
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