RawTherapee and darktable are primarily raw converters with their toolchain pipeline (RT) or pixelpipe (dt) suited to the conversion and development of raw files. One consequence of that is an early application of White Balance, which obviously makes sense for raw files – but does it also make sense when working with converted files (jpegs, tiffs, etc.)?
I have come across this issue when playing around with a swapped channels ICC profile as a result of this discussion in DxO PhotoLab’s forum. To illustrate my point here let me show you a regular sRGB file:
I converted this file to a swapped channels sBRG profile I made with DisplayCal (powered by ArgyllCMS and @gwgill):
The converted file with the embedded sBRG profile can be found here. Both files should look almost identical in any colour-managed application.
darktable doesn’t render the preview thumbnail correctly for me in the lighttable space, but it looks OK in darkroom. RT is fine as well, but the problem starts when I try to modify the white balance: the Temp and the Tint sliders work on wrong channels because WB is applied before the input profile. So when I try to warm the image up and move the Temp slider right, it cools it down instead:
So here’s my question: is it appropriate to apply WB before the input profile to a regular RGB file? Would it be a problem with e.g. ProPhoto RGB files? I know that Lightroom / Adobe Camera Raw applies WB to RGB files after the input profile. DxO PhotoLab and Capture One behave like darktable and RawTherapee – they follow the raw pixelpipe / toolchain pipeline.
Edited to add: I know that theoretically one can re-order the pixelpipe in the latest darktable but for some reason I couldn’t move the WB module after input profile.