[Digikam-devel] What do we want to store in the database?

[Gilles Caulier]

2007/8/31, Marcel Wiesweg <marcel.wiesweg at gmx.de>:
>
> > Dnia środa 29 sierpień 2007, Marcel Wiesweg napisał:
> > > Hi,
> > >
> > > It is a long-planned task for the next release to store more
> information
> > > than currently in the database.
> > > We are currently collecting which fields exactly we want to add.
> > >
> > > To qualify for inclusion, IMO a field should fulfill one of these two
> > > criteria:
> > > - the field can be of interest in connection with the image it belongs
> > > to - searching for the field is a considerable feature
> > > AND this criterion:
> > > - the information is usually available for images in a common usage
> > > pattern of digikam
> >
> > I think we can split all data about image in 3 parts:
> >
> > - information about file
> > - information about image ("hardware")
> > - metadata, here I think the best choice (as industry standard) is "IPTC
> >   Core"
> >
> > > Currently I have these fields on my list:
> > >
> > > - comment
> > > - rating
> > > - creation date
> > > - modification date
> > > - size ( dimensions in pixels)
> > > - color depth (8, 16)
> > > - color model (RGB, CMYK, ...)
> >
> > - If px size is included why not weight (size in KB/MB)? I know it can
> >   be read from filesystem but putting info in db could make some queries
> >   faster
>
> Yes I think about it.
> It comes together with modification date. Both need to be updated after
> edits.
> Makes sense.
>
> > - all path related things (Album path, name of file)
>
> That was implied ;-)
>
> >
> > > - make of the camera
> > > - model of the camera
> > > - aperture
> > > - focal length
> > > - focalLength as for 35mm film
> > > - exposure time
> > > - exposureMode
> > > - exposureProgram
> > > - sensitivity
> > > - flash
> > > - whiteBalance
> > > - orientation
> >
> > - metering mode
> > - focus mode
> > - file number (although it can have different formats so its usefulness
> >   can be questionable)
>
> Are these available from libkexiv2?


Yes and no. This is depand where data are store : in standard Exif or in
Makernotes.

Standard Exif is not a problem to extract. Tags name and value are define in
Exif spec.

http://www.exiv2.org/metadata.html

Makernotes is a big problem. A lots of code need to be written to check all
possibilities. Nothing is standardized.

This is why i recommend to host only the Exif Standard tags in a first time,
and progressivly to add Makernotes. Look my previous post for details.



Will someone want to search for the file number, will it ever be displayed
> in
> the "Properties" sidebar tab (or only in the metadata tab?)
>
> > Big question is handling of metadata. I'd like to see whole IPTC Core
> > put into database... For fast querying of those items and making it
> > independent of actual images.
>
> How many fields does that make?


It's bigger. Look here :

http://www.exiv2.org/iptc.html

We need to choose the most important.

Unforget than the new standard is XMP, which remplace IPTC. In general we
found a lots of tags IPTC in XMP, but few have been removed, and new have
been added. I recommend to use XMP as ref.

http://www.iptc.org/IPTC4XMP/

Gilles
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