Brightness control in Ubuntu. After typing this command the screen becomes unreadable:
$ xrandr --output HDMI1 --brightness 45
This is because the number should be between 0 and 1. For example, this works:
$ xrandr --output HDMI1 --brightness 0.45
If you prefer GUI, you can use this Python script:
Please note that this is a "software brightness control". This will not change the brightness of the backlight. For most monitors it is better to set brightness of the backlight to 100% and correct the "software brightness" to comfortable level, because of too low frequency of the pulse-width modulation used for regulating the brightness of the backlight. Some monitors use PWM even when brightness is set to 100%.
About dangers of regulating the brightness with low frequency PWM:
You can change the "hardware brightness" (the actual brightness of the backlight) by using xbacklight, setpci or /sys/class/backlight/intel_backlight/brightness.
Do not use xgamma for regulating the brightness because this will not work correctly.
Read more here: http://askubuntu.com/questions/149054/how-to-change-lcd-brightness-from-command-line-or-via-script
There is a way to change the frequency of the backlight if you use Intel i915:
Tags: Brightness control in Ubuntu, Brightness, xrandr, brightness.py, Linux, Xorg, software bug, Ubuntu (Software), Ubuntu (Operating System)