KDE has an API to control display brightness. It is changeable, as the KDE Addon “control center”, mimicing macOS, is able to use 1% intervals.
Especially on Fedora the step between 0% and 5% is too big (logarithmic?) and I would like to change this and of course maks it public how that works.
Is there a lowlevel way or would it require deep system modifications? I cant imagine that, thinking that the addon works like that.
the step between 0% and 5% is too big (logarithmic?)
On the contrary, the default brightness control in KDE is linear, while the human eye light perception is approximately logarithmic. That’s why the perceived light change on the lower brightness levels is so big, while at the same time the change on the higher levels is barely noticeable.
I found this KDE bug report (448459 – Logarithmic brightness scaling) that also mentioned this merge request (https://invent.kde.org/plasma/powerdevil/-/merge_requests/134), but it seems no changes on the KDE side have been implemented yet.
What, apparently, have been done by KDE though, is there is now a way to control the brightness in 1% steps which have been added to Plasma 6.0 (more on that here — PowerDevil in Plasma 6.0 and beyond - KDE Blogs).
There is also a workaround solution that translates linear brightness control to set logarithmic brightness levels (https://github.com/Type-Here/kde-logarithmic-brightness)
It works for me on the latest Plasma 5 and, according to the author, should also work on Plasma 6.