I wanted to learn the channel mixer module in darktable with the help of a simple test picture with a black background and the different main color spots. Therefore I created such a picture in gimp.
Black background RGB 0 0 0, then red 255 0 0, green 0 255 0, blue 0 0 255 and some mixed colors.
As it turned out, in darktable analyzing the picture I did not get a black as expected.
Black turned out to be 13 14 14 and all the other colors had different too.
Long story short: I found out that this feature? is connected to my system color profile. When I switch to one of the other display profiles the RGB values are as expected.
It was just recently that I set up a color profile on my computer, i.e. I have little experience with it.
I presume that my color profile is somehow corrupt. Am I right? Does anyone have any idea how I can fix this? (I’m running Manjaro 18.1.5 with XFCE)