Redshift

Should’ve used this sight saver. FREE | JONLS.DK/REDSHIFT

Perhaps you’ve read about the highlights of the new Gnome 3.24 release, which will shine in the upcoming Fedora 26 (it should be out when you read these words). We’re talking here about the blue light filter, or ‘night light’ in terms of Gnome. The idea is to automatically adjust the colour temperature of your screen depending on the time of day. Science tells us that warmer, yellowish tones are much better for our eyes if we have to spend hours in front of computer displays in the evening or at night. However, if you run a different desktop environment, this feature is available to you via the third-party app Redshift.

Essentially, the application has two parts: the daemon that does the real job, and the GUI that lets you control Redshift settings without going to the Terminal. Automatic gamma correction doesn’t depend on your display’s physical interface (so an old VGA cable is no problem), but instead relies on RANDR support in your graphics driver. In other words, each and every Linux desktop system should be supported.

Redshift assumes that the neutral colour temperature is 6,500 K, while the most ‘warm’ night mode matches 4,000 K. The daemon calculates the value for the specific time of the day and sets gamma with smooth, hardly noticeable transition. To guess the time of day, Redshift needs to know your location. You can manually set latitude and longitude, or rely on an automatic mechanism that uses Geoclue to determine your location based on IP.

Most Linux distros provide Redshift within standard repositories. Once you’ve installed it, check whether the service is running with the following: $ sudo systemctl status redshift.service You need to replace status with enable in the command above if Redshift is not running.

Now you can start configuring the software using either Redshift GTK indicator or Redshift plasmoid, depending on your desktop.

You don’t need to wait for sunset in order to see Redshift in action — the icon in the system tray lets you manually adjust the colour temperature using your mouse wheel, which gives you an immediate impression of how to use it.