[Digikam-devel] [Bug 279255] New: white balance method "camera" does not use the camera's values

[S. Burmeister]

https://bugs.kde.org/show_bug.cgi?id=279255

           Summary: white balance method "camera" does not use the
                    camera's values
           Product: digikam
           Version: 2.0.0
          Platform: openSUSE RPMs
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: RAW files management
        AssignedTo: digikam-devel at kde.org
        ReportedBy: sven.burmeister at gmx.net


Version:           2.0.0 (using KDE 4.7.0) 
OS:                Linux

If one issues dcaw on a RW2 picture with the "-w" option it shows the values
for white balance the camera set.

If digikam is set to "camera" for the "white balance method" it should use
those exact values.

However digikam's output shows that it uses different values.

dcraw:
Scaling with darkness 15, saturation 4095, and
multipliers 1.901141 1.000000 1.745247 1.000000

digikam:
Scaling with darkness 0, saturation 4080, and
multipliers 1,000000 0,526000 0,918000 0,526000

dcraw_emu from libkdcraw:
Scaling with darkness 0, saturation 4080, and
multipliers 1.901141 1.000000 1.745247 1.000000

As you can see digikam as well as dcraw_emu use the wrong values for darkness
and saturation.

dcraw_emu uses the correct values for the multipliers while digikam does not
use those absolute values, i.e. strictly speaking does not use the camera's
white balance but only its ratio. Since this does make a difference it should
only be used if the user enabled it!

In case the absolute white balance values blow a channel it might make sense to
have a darker image but no blown channels – but only as option, e.g. "use value
ratio".

Reproducible: Didn't try

Steps to Reproduce:
Isse dcaw -w, digikam and dcraw_emu on a RAW picture (RW2 in this case) and
compare the values.

Actual Results:  
different values

Expected Results:  
same values.

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