[Digikam-users] 2 DNG questions

Gilles Caulier caulier.gilles at gmail.com
Thu Jan 8 19:22:42 GMT 2009

2009/1/8 Gandalf Lechner <gandalf.lechner at univie.ac.at>

> Hello,
> since I like the idea of a generic raw format, I played a bit with the DNG
> converter in digikam and observed two things I would like to ask about.
> 1) The DNG files produced by the converter from my Canon CR2 raw files are
> smaller in size, even with full size JPEG preview embedded. Typical size
> differences are 13 vs 10 MB. So I wonder if I loose data in the conversion
> -
> is there some compression going on?

DNG use JPEG lossless compression with 16 bits color depth support.

You don't loose quality of course.

> 2) Some metadata get lost in the conversion, like ISO setting and lens
> focal
> range, and the camera name changes from "EOS Kiss Digital X" to "Canon "EOS
> Kiss Digital X". Is the loss of metadata due to my digikam settings or a
> limitation of the current implementation of the converter?

It's a limitation of.. DNG sdk from Adobe where Metadata are not supported
as it must be.

I have talk with Andreas (from Exiv2 project), and some issues are possible
to strap DNG adobe metadata management and use Exiv2 instead. I need to
re-test with current Exiv2 implementation from svn and check if last
problems with writting support to DNG are solved now.


Gilles Caulier
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