[Digikam-devel] better metadata support : added exiv2 depency ?

[F.J.Cruz]

El Martes, 14 de Febrero de 2006 15:55, Gilles Caulier escribió:
> Hi all,
>
> To support better metadata, especially Exif and IPTC, we need to use a new
> lib. Exiv2 seem to be the better choose actually, to manipulate EXIF and
> IPTC metadata from image file.
>
> http://home.arcor.de/ahuggel/exiv2/
>
>  Actually, Exiv2 support :
>
> - Exif data from JPEG files with a large suppport of special marker notes
> from constructors.
> - IPTC data from JPEG files
> - Exif data from CRW RW file (Canon tm)
>
> In Digikam::DImg, metadata are just stored like bytes array (DImg is a
> metadata container, no a metadata parser). It's easy to move this metadata
> from an original image to a target image. Actually, JPEG<->PNG Exif/IPTC
> metadata preservation is complete. If you convert a JPEG file including
> Exif data to a PNG file using Image Editor (and vis-versa), you can see the
> Exif metadata including to PNG file with Exif tab from main interface. Look
> here :
>
> http://digikam3rdparty.free.fr/Screenshots/digikam0.9.0-alpha4.png
>
> Exif/IPTC are store to PNG using standard ImageMagick Raw profile tag...
>
> But we need more metadata preservation :
>
> - RAW Exif/IPTC extraction
> ==> http://www.rags-int-inc.com/PhotoTechStuff/RawStandards/RawSummary.html
> - TIFF/EP Exif/IPTC manipulation.
> - DNG Exif/IPTC manipulation (DNG==TIFF/EP like file. We can plan this file
> format for the future).
>
> Exiv2 will support others image file format in the future, especially more
> RAW files and TIFF/EP files.
>
> In all case, Extracting RAW Exif metadata is possible using dcraw::parse.c
> method. This way is used in neftags2jpeg program dedicaced to extract Exif
> from NEF file :
>
> http://pages.quicksilver.net.nz/pepe/d70/Nikon_D70_on_Linux.html#exif
>
> neftags2jpeg program using Exiv2 to store like a byte array Exif
> informations (:=)))...
>
> In digiKam, this way can be used to make a RAW file parser to extract Exif
> data until that Exiv2 support better RAW file format. To get a complete
> list of RAW file tags, we can get any inspiration from the great exifprobe
> program :
>
> http://www.virtual-cafe.com/~dhh/tools.d/exifprobe.d/exifprobe.html
>
> If we using Exiv2 for 0.9.0, we will using 2 lib about Exif : Exiv2 and
> libkexif (using libexif). Sure in the future, all code depending of
> libkexif must be ported to Exiv2, but this can do later 0.9.0...
>
> Note : Exiv2 Exif bytes array data is compatible with libkexif. We can
> extract exif metadata using Exiv2 and displaying that using libkexif
> without problem...
>
> Any suggestions welcome.
>
> Gilles Caulier

After I have seen some possible choices, I think that exiv2 is the best one at 
this moments, so I agree with Gilles.

To Gilles: if I get to finish de icc stuf some day I would like to help you 
with metadata code :-/

Paco.