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

[F.J.Cruz]

El Miércoles, 1 de Marzo de 2006 23:06, Caulier Gilles escribió:
> Le Mardi 28 Février 2006 04:51 PM, Andreas Huggel a écrit :
> > Hi,
> >
> > Thanks for using Exiv2!
> >
> > On Tuesday 28 February 2006 19:39, Gilles Caulier wrote:
> > > Le Mardi 28 Février 2006 11:09, Gilles Caulier a écrit :
> > > > Hi all digiKam users/team,
> > > >
> > > > Like you have seen last week, I have started a new implementation of
> > > > metadata viewer using libExiv2 instead the current Exif viewer using
> > > > libkexif.
> > > >
> > > > A fresh screenshot can be seen here :
> > > >
> > > > http://digikam3rdparty.free.fr/Screenshots/digikam0.9.0-alpha6.png
> >
> > Nice pictures. I noticed that the metadata is shown as plain values as
> > opposed to human readable strings, e.g., "ResolutionUnit 2" as opposed to
> > "ResolutionUnit inch". Can the user change that with the "Level of
> > detail" setting ("Simple" sounds like not everything is shown though)?
> > Especially for makernotes, the more readable expressions might be more
> > useful than plain values. You can get these easily by using the output
> > operator for Exifdatum.
>
> I have tried to do it like this :
>
>         for (Exiv2::ExifData::iterator md = exifData.begin(); md !=
> exifData.end(); ++md)
>         {
> ...
>             Exiv2::Exifdatum ed = exifData[md->key().c_str()];
>
> ...
>         }
>
> ... but after, i need to do what exactly ?
>
> And another question : how to get a more user friendly value of tag. The
> Exif data are sometime uninterpreted number values instead of strings. EG
> for a Nikon Camera there is a FlashpixVersion string which ist shown as 48
> 49 48 48 probably meaning 1.00.   Other things like exposure time (and many
> more) are displayed as a fraction (10/200) instead of a clearer value
> (1/20). This kind of interpretation problems happen in many other EXIF tags
> as well.
>

In Nikon NEF files (and probably other raw formats) there are some "fields" 
that are composite tags, for example,  LensID is constructed as a Composite 
tag from the raw hex values of 8 other tags: LensIDNumber, LensFStops, 
MinFocalLength, MaxFocalLength, MaxApertureAtMinFocal, MaxApertureAtMaxFocal, 
MCUVersion and LensType, in that order.

Paco.