Ubuntu – Screen brightness control not working on Lenovo T530

I installed Xubuntu 12.10 on my new Lenovo Y500 and also could not adjust brightness, it was at at maximum and could not be controlled. Get installed and used graphics driver:

lshw -c video

Gave me:

configuration: drigver=nouveau latency=0

• changing the value in /sys/class/backlight/acpi_video0/brightness does not change brightness
• booting with acpi_backlight=vendor does not change brightness
• etpci -s 00:01.0 F4.B=XX (XX = 00 to ff) does not change brightness

For the moment I solved this by installing the nvidia driver:

sudo apt-get install linux-source
sudo apt-get install linux-headers-generic
sudo apt-get install nvidia-current-updates

This gives you the terminal command:

sudo nvidia-settings 

Go to: DFP-0-(LGD), Tab: Color Correction

Here you can set the brightness.

I created a temporally bash script to adjust brightness level. Then I create 2 sortcuts at keyboard mapping settings to set up CTRL + Brightness UP or CTRL + Brightness Down with this script:

#!/bin/bash

# Step brightness value
STEP=2
# Max brightness value (defult 100)
MAX=100
# Min brightness value (defult 0)
MIN=0

COMMAND=$(xrandr --verbose | grep -i brightness | cut -f2 -d':' | tr -d "[:space:]")
ACTUAL=$(bc -l <<< $COMMAND*100 | cut -f1 -d'.')

while getopts ": u d" input
do
    case $input in
    u)  if [ $ACTUAL -lt $MAX ];then
                TOTAL=$(bc -l <<< $(($ACTUAL+$STEP))/100)
                $(xrandr --output DP-0 --brightness $TOTAL)
        fi;;
    d)  if [ $ACTUAL -gt $MIN ];then
                TOTAL=$(bc -l <<< $(($ACTUAL-$STEP))/100)
                $(xrandr --output DP-0 --brightness $TOTAL)
        fi;;
    ?)  printf "Usage: brightness [OPTION]\n"
        printf "Increase or decrease birghtness on Ubuntu Xorg.\n" 
        printf "WAYLAND MUST BE DISABLED\n\n"
        printf "  -u\t Increases brightness\n"
        printf "  -d\t Decreases brightness\n"
        exit 2;;
    esac
done

And in set custom shortcut I added this