2 DNG questions

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?

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?

Best,
Gandalf
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[Gilles Caulier-4]

2009/1/8 Gandalf Lechner <[hidden email]>

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.

Best

Gilles Caulier

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