Dim screen past the minimum on Ubuntu

Solution 1:

Here is a link specifically addressing setting screen brightness below the minimum:

Decrease Backlight Below Minimum – Ask Ubuntu

1. Open Terminal

2. Enter the following command:

   cat /sys/class/backlight/intel_backlight/brightness
   

3. Write down the resulting value (12421 in my case)

4. Divide value by 6 and write it down (2070 in my case)

5. Enter the following in the terminal, replacing 2070 with your value:

   sudo su -c "echo 2070 >/sys/class/backlight/intel_backlight/brightness"
   

6. Close Terminal

7. For future usage of the last command, open Terminal, press Ctrl and R together, start typing brightness. When the last command appears, just press Enter.

It works for me on a Samsung NC110 with Ubuntu 12.04.

Solution 2:

TLDR: Settings > Accessibility > Zoom

Here is a last resort for anyone who tried the above and was unsuccessful (and made it here almost a decade after the initial question).

My setup: Gnome, Wayland, Fedora 33, Dell XPS 15 9500

I'm not entirely up to date with Ubuntu, but if you're running Gnome and Wayland this might work for you.

You should be able to find in the Zoom feature via Settings > Accessibility > “Seeing” > Zoom. Here you should be able to modify brightness, contrast, color according to your preferences. Set magnification to 1.0 (unless you want your focus to follow the mouse around). If you run into weird lingering visual artifacts from the mouse you can enable the crosshair and customize the color to be transparent (I also have thickness and length set to the minimum, and unchecked the “overlaps mouse cursor”, although I’m not sure whether these settings matter).

Lastly, for convenience and easy toggling, via Settings > Keyboard Shortcuts there should be an option for “Turn zoom on or off” which you can map to an appropriate key binding (mine is set to “Shift + Monitor brightness down”). YMMV!

Credit goes to Bastien: https://bugzilla.gnome.org/show_bug.cgi?id=741224#c42

Solution 3:

you can also use "xgamma -gamma 0.5" command to decrease the intensity of RGB colors. See xgamma usage by using command "man xgamma". For my intel display the gamma brightness varies from 0 to 10(including decimal values).