12.12.2018

The Advent of Void: Day 12: redshift

If you stay up late working on packages and system security patches, you may notice after a while your eyes start to hurt. This is likely due to too much blue light at night, which studies have shown can cause eye strain. While glasses and monitors that can filter this light out are one solution, you can also adjust values in software to account for this blue light at night.

Doing this by hand is obviously tedious, so there’s an excellent software package called “redshift” which does this adjustment for you.

Once installed from the repos (xbps-install redshift) create a file like so that configures it:

[redshift]
temp-day=5700
temp-night=3200
gamma=0.8
location-provider=manual
elevation-high=24.69

[manual]
lat=39.109489
lon=-76.772980

This file should be in ~/.config/redshift.conf

The fields are pretty self explanatory, with the exception of elevation-high which is the solar elevation in degrees before its considered to be daytime. All temperatures are provided in Kelvin, and the wikipedia page on color temperature has a nice chart showing different values against the common sources of light that produce them.

From here, just start redshift with your session (redshift-gtk if you have an environment that can autostart .desktop files) to enjoy color filtered light at night!