[Digikam-users] demosaicing white balance method camera

[Remco Viëtor]

On Tuesday 02 August 2011 06:44:49 Gilles Caulier wrote:
> Good question. libraw used by libkdcraw and finally digiKam is the dcraw API
> (but not only).
> 
> In libkdcraw, there are some dcraw like command line tool to check
> functionalities.
> 
> Try to process your RAW file with it and look traces. It's the same than
> dcraw ?
> 
> Gilles Caulier
> 
> 2011/8/2 Sven Burmeister <sven.burmeister at gmx.net>
> 
> > Hi!
> > 
> > If I use dcraw with -w (camera white balance) to demosaic a RW2 file it
> > shows
> > the following:
> > 
> > dcraw -w -v P1030225.RW2
> > 
> > Scaling with darkness 15, saturation 4095, and
> > multipliers 1.901141 1.000000 1.745247 1.000000
> > 
> > If I open the same image in digikam's image editor (2.0) with "white
> > balance
> > method" set to "camera" the debug output shows:
> > 
> > Scaling with darkness 0, saturation 4080, and
> > multipliers 1,000000 0,526000 0,918000 0,526000
> > 
> > Should those not be the same numbers as above?

Yes and no:
the difference in darkness and saturation are strange, 
the white balance multipliers still have the same ratio though, 
so the applied white balance correction is identical.
digikam apparently has chosen to always keep the factors <= 1,
this has the advantage that you won't blow a channel due to the white balance 
correction. but of course the image will appear darker.

Remco