I missed quite a few things here. I won’t be able to answer to every post, but I read them all and they all give new hints and I am very glad for what I learned. So thanks again to everyone.
Yup ! Thanks a lot, I’ll try to dig into base curves. To be honest I kinda abandonned them since they are not recommanded with filmic. As a newcomer (both in darktable and in photography) I had to chose a workflow, and scene refered worflow seemed to be the way to go.
In that cas you use both filmic AND something that is similar to basecurve. Is this still a not-recommanded workflow ? (even if it works for you, it may be confusing for someone else)
EDIT : I guess this will be addressed in this post Darktable - Workflow approaches - Custom Base curves, LUTS, Filmic my bad
Yes, I can see why you feel that way. As other stated : sometimes OOC are just baselines. They seems “Ok” and you want to master your editing software to at least match that (even if the real goal is to make it better). That was my case, especially in the field of sharpness (I felt that in term of dynamic range, noise reduction, contrast, colors, … i was at (or above) OOC jpegs quality).
(This was about why contrast equalizer could be stacked)
To me this felt like that the first instance would increase the sharpness of small elements. The second instance will more easily detect these small elements (as they would appear bigger). All of this have to do with the wavelets and the frequency-space. This is just my intuition to help understand why it works, it might be wrong !
When I tried this I just decreased the mix on one of the instance (the second), not both.