[Digikam-users] Pentax PEF vs DNG in digikam

Karl Günter Wünsch kgw at mineralien-verkauf.de
Tue Sep 27 18:42:38 BST 2011

On Tuesday 27 September 2011, Gilles Caulier wrote:
> DNG is not lossy format, especially metadata. All is preserved, as 
This most certainly is wrong. Even (or especially) the Adobe RAW to DNG 
converter at times has reinterpreted (I would go as far as saying 
misinterpreted) some of the metadata - while preserving the original maker 
notes which no one can do anything useful with in a DNG - resulting in for 
example wrong black value data which couldn't be corrected because that data 
had been falsely derived from some discarded rows and columns of the sensor...
> The problem is the way  to demosaicing and post process DNG. It sound
> like not all process is done in DNG against PEF. This is why image is
> dark (no gamma and WB adjustements). These informations are taken in
> makernotes, of course.
They are supposedly taken from the transcribed (from native to DNG standard) 
maker notes. As I read the DNG standard, the original maker notes are still 
available but must not be used if the DNG standard ones are in existence.
> How to solve it. libraw used by digiKam must be patched in to use
> makernotes, for all possible camera makers. This is a huge job, not
> simple.
It's a job which is a useless waste of effort as the existance of solutions 
like digikam, ufraw or rawtherapee (all open source and fast evolving 
applications) simply make DNG as a format obsolete. There simply is no need 
anymore to convert your images from one propriarity file format to a one 
propriarity file format (DNG is just a propriarity file format from a 
manufacturer who doesn't produce a camera) because the ability to process the 
original RAW files may be lost...
Karl Günter

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