autobright

Homemade automatic screen brightness adjustment for notebooks with webcam

It uses notebook's webcam to take a picture, and then measures the resulting image's white pixels intensity. This can be correlated with ambient luminosity to adjust notebook's screen brightness and also toogle on/off keyboard's led.

If you wish, you can start a service for adjusting brightness upon resume from suspend (check the .service file which comes with the repo).

Last but not least, you can crontab this script to periodically adjust your screen brightness as well.

Dependencies

sudo apt install brightnessctl ruby fswebcam

gem install mini_magick

Instalation

First you need to discover your devices. For doing that cast brightnessctl -l. For example, mine are

Available devices:

Device 'intel_backlight' of class 'backlight':
	Current brightness: 27600 (23%)
	Max brightness: 120000

Device 'phy0-led' of class 'leds':
	Current brightness: 1 (100%)
	Max brightness: 1

Device 'input3::numlock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'input3::capslock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'input3::scrolllock' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

Device 'dell::kbd_backlight' of class 'leds':
	Current brightness: 1 (50%)
	Max brightness: 2

Device 'platform::micmute' of class 'leds':
	Current brightness: 0 (0%)
	Max brightness: 1

where my screen backlight is intel_backlight and keyboard is dell::kbd_backlight. Once you have discovered both devices, put them into autobright.rb. If keyboard backlight is not present, just comment the corresponding line in autobright.rb (look for an annotation).

You will also need to tweak the log_file and snapshot_file variables in order to meet your needs.

You may now clone the repo, and make autobright executable (chmod +x autobright.rb). Just run it as ./autobright.rb.