May 2025

Bluelight screen filter for linux/X11

There is an extremly simple way to remove the blue light from your linux computer during the evening. You don't need to install anything all the software is already part of X11. The command xgamma allows you to perform monitor color corrections. This sets e.g the RGB values all to 100%:
xgamma -rgamma 1.0 -ggamma 1.0 -bgamma 1.0

In the evening you can simply run:

  xgamma -rgamma  1.0 -ggamma 0.8 -bgamma 0.7

to reduce the blue light from your screen. This causes less distrubence to the natural cycle of your body. You can play with those values (e.g xgamma -rgamma 1.0 -ggamma 0.7 -bgamma 0.6 ).

The values reset at logout/login and you have to run the xgamma command again if you use your computer in the evening. I have created a bash alias called bf (bluelight filter):
alias bf='xgamma -rgamma 1.0 -ggamma 0.8 -bgamma 0.7

Social media and screens are the one addiction that no one talks about: blue light and dopamine hijacking. Constant dopamine hits from social media, news, and notifications are a problem. Don't look at news or social media and dimm down the screen colors towards the evening. Relax and calm down before you go to bed.