Comment 36 for bug 429942

Ok, I found how the brightness can be adjusted by editing a text file:
1) Open a terminal and type sudo su to get root permissions
2) chmod 711 /sys/class/backlight/psb-bl/brightness to give permission to yourself to read/write the text file in question.
3)Use a text editor to open the text file, in the example it's leafpad: leafpad /sys/class/backlight/psb-bl/brightness
4) Choose a number from 1 - 100. You 'll probably want to set it somewhere inbetween (around 50 is ok). Save and you're done.