After updating ubuntu to 19.04, I noticed that the minimum brightness of my laptop was higher than that of 18.04.
Set the screen as dark as the graphical interface allows me and works
cat / sys / class / backlight / intel_backlight / brightness reports 1200.
To confirm this, I've loaded my usb with Ubuntu 18.04 to start live.
If you restart the same command, the 1.Max brightness is fixed at 120000; it is still very dark, but I would appreciate having this very dark back.
The laptop in question is a Dell XPS 15 9570.
I've tried setting some startup parameters, such as acpi_backlight = video / vendor / native, but nothing seems to allow me to set the brightness to 1, they all stop at 1200.
I've since figured out how to change the brightness by doing
sudo su -c "echo 1> / sys / class / backlight / intel_backlight / brightness" and the screen darkens an appreciable amount. So I am curious to know if the brightness range of the GUI is 1-120000.