xscreenfilter

Protect your eyes. Manage your screen brightness and temperature in linux.

This script lets you apply screen filters that modify your screens' apparent brightness and temperature.

This script does not change the actual hardware brightness, also called backlight. For backlight, I recommend the brightnessctl command.

Installation

Either download a precompiled binary or compile the xscreenfilter.c file by simply running:

sudo apt install libxrandr-dev libx11-dev
curl https://raw.githubusercontent.com/caph1993/xscreenfilter/master/xscreenfilter.c > xscreenfilter.c
gcc -I/usr/local/include -L/usr/local/lib xscreenfilter.c -o xscreenfilter -lXrandr -lX11
# Optional (clean)
sudo apt remove libxrandr-dev libx11-dev

Tested in Linux Mint 21 on October 2022.

How to use?

Place the file in ~/.local/bin or /usr/local/bin, and add global hotkeys for these two commands:

• xscreenfilter -350 -0.05 (darker and warmer, better for the eyes)
• xscreenfilter +350 +0.05 (lighter and cooler).

Command line usage. Usage by examples:

• Run ./xscreenfilter 4500 0.9 to set temperature to 4500K and software brightness to 0.9.
• Run ./xscreenfilter -1500 +0.0 to decrease current temperature by 1500K and maintain brightness at its current level.
• Run ./xscreenfilter 4500 +0.1 to set temperature to 4500 and increase brightness by 0.1.
• Run ./xscreenfilter to set temperature to 6500K and brightness to 1.0 (default values).

Motivation of this script

• We spend many hours on the screen.
• Screens are too bright, even on 1% backlight.
• xrandr supports brightness but not temperature: there is a --gamma option but colors look very strange if you use it.
• redshift supports setting both, but not reading, increasing or decreasing. It is meant for automated use only, making things darker at night. In my opinion, it is more practical to let the user change it directly, because if the window is closed during the day or the lights are on during the night, the automated system stops being useful. Furthermore, redshift has tons of dependencies and uses your location by default. In my opinion, it is too complex for such a simple task.
• sct is great, it was just missing the ability to increase or decrease.

Credits to:

• https://flak.tedunangst.com/post/sct-set-color-temperature
• https://github.com/mgudemann/sct