Hi,

I'm sure this has been discussed before, but I just can't find it. Why
is it that given the same shot, darktable/digiKam (showfoto) and
UFRaw/RawTherapee display different values for temperature and tint?
Process:
1. open grey card (WhiBal) shot in darktable and ufraw.
2. read spot white balance in darktable -> card really turns grey
3. note RGB multiplier values (in my case: 1.139, 1, 2.633) and
temperature/tint (3447K and 1.138)
4. open image in ufraw, set the same RGB multipliers -> card turns
grey, temperature and tint very different (2570K, green: 0.95)
5. open image in showfoto, set WB to manual, enter darktable's values
(T: 3447K, Green: 1.14) -> card turns grey
6. open image in rawtherapee, apply ufraw's values (Temperature: 2570,
Tint: 0.95) -> card turns grey

If memory serves me well, RT is based of dcraw; ufraw too, while
darktable uses both rawspeed and libraw (dcraw), but I think for my
Nikon D7000 it's rawspeed. Is this related? How is one to interpret
temperature?
For higher temperatures, the difference is smaller, but still present,
e.g. a sunlit shot with camera white balance is shown with temperature
= 5291K in darktable and as 4710K in RT; a shot in partial shade 6124K
in dt and 5928K in RT (reading the same camera multipliers).

Thanks,
Kofa

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