The Night Light filter, also known as Blue Light filter or Color Temperature filter, is a bit hard to find in Ubuntu 20.04. The Night Light tab is now in shown in the title bar, next to the Displays tab. These 2 tab labels look like they are just a title, but in fact they can be clicked on. (BTW it's Settings -> Devices -> Displays: Night Light in Ubuntu 18.04.) Another tidbit: there are some reports that using a Blue Light filter does not really affect your reaction to viewing a screen such as affecting your sleep; you may wish to do your own research!
The Night Light filter, also known as Blue Light filter or Color Temperature filter, is a bit hard to find in Ubuntu 20.04. It's found here:
- Open the Show Applications by clicking on the 9 dots in the lower left of the screen.
- In the 'type to search' textbox (top of screen), type 'Settings'; click on the Settings icon to open the Settings app.
- In the Settings window, choose Displays in the left-side list of setting topics.
- In the title bar at the very top of the window, choose the Night Light tab.
- Turn on the Night Light / blue light filter using the on/off slider.
You can either use the built-in automatic schedule or switch to Manual Schedule using the combobox labeled 'Schedule'. Set the times and the color temp to your preferences. (I set the times as 00:00 to 23:59 so the filter is on all the time.
For CLI lovers like me, you can also do it using
gsettings set org.gnome.settings-daemon.plugins.color night-light-enabled true
gsettings set org.gnome.settings-daemon.plugins.color night-light-enabled false
gsettings, you'll be able to make a custom script to just turn it on or off without worrying about the time schedule like so:
To set the starting hour :
gsettings set org.gnome.settings-daemon.plugins.color night-light-schedule-from 12.0
To set the ending hour :
gsettings set org.gnome.settings-daemon.plugins.color night-light-schedule-to 11.9
Here I chose 11.9 as ending and 12.0 as beginning to have it active all day long when it is enabled.
Hope it helps!
For Gnome customization lovers, there is 2 extensions that make anyone eyes life easier:
- Toggle Night Light by cansozbir: Add an night light toggle to the top bar.
- Night Light Slider by TimurKiyivinski: Add an night light slider to control color temperature to the top bar dropdown menu.
Both work together perfectly, with the night light slider hiding when disabled.
Also, on the night light settings UI, the slider responsible for setting the color temperature seems to offer a range from decently orange-yellowish to extremely orange yellowish. What I mean, even the minimum value may come across as too yellow to some.
This value however can be adjusted manually as well; either via the graphical interface offered by the app
dconf-editor, or via the gsettings api from the terminal as such:
gsettings set org.gnome.settings-daemon.plugins.color night-light-temperature 5800
For reference, the value for no colour shift at all would be 6500.
A value around 5800-6000 offers a noticeable, but not overdone warm effect.
Following this helped me: https://www.reallinuxuser.com/how-to-change-default-color-temperature-values-of-redshift-at-startup/
- Type “startup” in the search bar of the applications menu and click on “Startup Applications”.
- In the following screen look up Redshift.
- Click on the Edit button.
- Type in the Command field “redshift-gtk -t 6500:2500” and click Save.
Now restart your machine or just Log Out and Log in again and you will see that the night time color temperature will automatically be set to 2500 kelvin.