Introduction on Android
On Android there are 2 ways to reduce the display brightness to lower than normally possible. One is the built in “extra dark” which applies a set transparent black overlay on top of the display. The other one is “Red Moon” which is more customizable and allows blue-light filtering and a customizable dark overlay.
As phones use OLED screens, this works perfectly and actually reduces the brightness of all non-black elements well.
My Laptop has an IPS display so it should have true black colors, but I am not sure about the other brightness gradients. I assume this would work equally well though.
KDE builtin tool
KDE Plasma has a builtin tool for blue-light reduction and it works great. But it lacks the dark overlay feature to reduce the overall brightness.
Plasmoid, gammastep, redshift
There is a Plasmoid called “Redshift control” and it allows using redshift or gammastep.
I tried both tools, and I am not sure if they work on wayland at all.
Redshift is abandoned and has no wayland support afaik.
gammastep
Error: Could not control gamma, exiting.
Error: Failed to start adjustment method: wayland
Gammastep supports wlr-gamma-control-unstable-v1 protocol for wlroots-based
wayland compositors.
So I assume no kwin support yet. Waycheck flatpak shows me “N/A”, I will try the Fedora package for more access.
The dev recommends to disable these gammastep things
rm ~/.config/autostart/gammastep-indicator.desktop
systemctl --user disable --now gammastep-indicator
systemctl --user mask gammastep-indicator
systemctl --user disable --now gammastep
systemctl --user mask gammastep
Other options?
I tried to find a KWin script but not sure if that is the right place to search.
Anyone know if such a thing exists?