How do I decrease brightness of my laptop beyond the amount it specifies?

Question

Is there a way I can decrease the brightness of my laptop (Dell 1558) beyond the amount it actually allows me to?

I tried Redshift, it works okay, but I wanted to manually decrease the brightness. There was an app I came across in Windows named Dimmer and it worked perfectly, but I couldn't find its Ubuntu counterpart.

Answer 1

For regular operation on your backlight you can use xrandr and xbacklight, but that will not get beyond its regular limits.

Try to find your kernel's backlight interface.

find /sys -name "*backlight*"

For my system, it is provided in the /sys/class/backlight/nvidia_backlight folder where I can use the files

• actual_brightness
• bl_power
• brightness
• max_brightness

to test things out. For example:

# cat max_brightness 
127
# cat actual_brightness 
127
# echo 60 > brightness # <-- here it actually decreases my backlight
# cat actual_brightness 
59

If you're using an nVidia GPU you could try out nvidiabl or even patch the source in nvidiabl-laptops.h to override default min/max values to fit your needs.

However -- keep in mind that forcing it beyond its limits may damage your hardware.

Answer 2

The question has been answered here: How do you change brightness, color and sharpness from command line?

On my Dell laptop:

xrandr --output LVDS1 --brightness 0.8

You can run the xrandr command to see the name of your screens.

Answer 3

http://www.iasptk.com/save-screen-brightness-settings-in-ubuntu-1204-laptop

Some Ubuntu laptops screen brightness reset to the lowest or highest on every boot and you have to configure the screen birghtness on every login.

To save the screen brightness settings in Ubuntu laptop.

Open a terminal window, and execute this command to edit /etc/rc.local:

sudo nano /etc/rc.local

Add this before the last line “exit 0″:

echo 5 > /sys/class/backlight/acpi_video0/brightness

number 5 is the value of your screen brightness. With this command check the maximum:

cat /sys/class/backlight/acpi_video0/max_brightness