I already follow these instructions provided in Ubuntu StackExchange and display is still reset to minimum after restarting.
cat /sys/class/backlight/acpi_videoX/brightness gksu gedit /etc/init/fixbrightness.conf description "Sets brightness after graphics device is loaded" start on graphics-device-added task exec /bin/echo BRIGHTNESS_VALUE > /sys/class/backlight/acpi_videoX/brightness
cat /sys/class/backlight/acpi_video0/max_brightness`<br> gedit /etc/rc.local`
Add the line below before the last. Change the number 0 to the brightness level you want.
echo 0 > /sys/class/backlight/intel_backlight/brightness #I set 9 here.
3- Update Grub file, line no 11 in /etc/default/grub to:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor" update grub using the command update-grub
sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf
Add the following lines to this file:
Section "Device" Identifier "card0" Driver "intel" Option "Backlight" "intel_backlight" BusID "PCI:0:2:0" EndSection
sudo add-apt-repository ppa:nrbrtx/sysvinit-backlight sudo apt-get update sudo apt-get install sysvinit-backlight
Im using intel video card for brightness. Backlight found at: