[Digikam-devel] Image Metadata extraction : implementation progress...

[F.J.Cruz]

El Miércoles, 1 de Marzo de 2006 17:49, Caulier Gilles escribió:
> Le Mercredi 1 Mars 2006 17:15, F.J.Cruz a écrit :
> > El Martes, 28 de Febrero de 2006 14:08, Gilles Caulier escribió:
> > > Le Mardi 28 Février 2006 12:22, F.J.Cruz a écrit :
> > > > Of course,I'm very interested on metadata support in digiKam,
> > > > especially NEF files since I'm owner of a D50.In fact, along this
> > > > last week I've been having a look to exiv2 code and I want to make
> > > > you some questions:
> > > >
> > > > - How are you going to implement metadata infor for files that are
> > > > not implemented in exiv2 yet?
> > >
> > > The better way that i have identifed to add better RAW file support is
> > > to re-use implementation from ExifProbe project :
> > >
> > > http://www.virtual-cafe.com/~dhh/tools.d/exifprobe.d/exifprobe.html
> > >
> > > I think that only a simple exif/markernote extraction is enought in
> > > digiKam at this moment.
> > >
> > > > Actually exiv2 has support only for CRW files
> > > > (one of the two Canon RAW formats, the other one is CR2), altough
> > > > there are files with makernotes specifications for a lot of
> > > > manufacturers, so if I want to implement metadata extraction for NEF
> > > > files, have I to implement the equivalent to crwimage in Exiv2? this
> > > > can be a hard work if we have to do this for all the manufacturers
> > > > who provide RAW format.
> > >
> > > The ExifProbe have a very well documentated source code about. Each
> > > file format is separated cleanly. I think we can trying to use it.
> > >
> > > Each Digikam::DMetadata::loader are separate too. We can add new image
> > > file format loader progressivly without any risk.
> >
> > I want to write this stuff for nef files, but I need you give me some
> > tips about how to implement it (following the ideas  you described up)
>
> Well to start, i will use the code from this program :
>
> http://pages.quicksilver.net.nz/pepe/d70/Nikon_D70_on_Linux.html#exif
>
> the file http://pages.quicksilver.net.nz/pepe/d70/neftags2jpg.tar.bz2 is a
> small c implementation witch uses exiv2 ! It's extract any tags from a NEF
> file and contruct an Exif data container using Exiv2.
>
> You need to backport this code and put it on a new file to link with the
> dmetadata::rawloader.
>
> You can certainly get more tags using ExifProbe implementation, but you
> need to study  ExifProbe implementation. It's more complicated.
>
> > > > - What's about "write-access" on iptc data?
> > >
> > > With Exiv2 you can write IPTC tag in image, CRW included.
> > >
> > > > - Which of all  these changes are for 0.9.0?
> > >
> > > Right question. I need any report about my patch with the current
> > > implementation before to commit anything.
> >
> > About the new exif/makernotes/iptc viewer looks fine but there is a lot
> > of work to do and not only for other raw files. There is some fields and
> > a lot of values that are not in "human-readable" format so we need  a
> > "dictionary" to translate this stuff to something that anybody can
> > understand. If we have exiftool as reference, you can understand what I'm
> > talking about.
> >
> > So if you give me some tips, as I've said, I can start to implement
> > metadata stuff for nef files (or other files format you want), until we
> > have a final decision about color management issue.
>
> Yes i seen. Look like Exiv2 author have send any tips on the ML to improve
> this problem. I will fix it.
>
> Gilles

Ok, I'll try to start with neftags2jpg stuff.

Paco.