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I am not able to change the screen brightness on lenovo z570.

Even the function keys for the brightness are also not working. Any idea ?

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If all else fails, you might want to try out the command line utility xbacklight.

You can install it by running

sudo apt-get install xbacklight

Then if you want to make the screen brighter you can type

xbacklight +50

(or replace 50 with whatever percentage you'd like)

Or if you wanted to dim the screen you can type

xbacklight -50


Also if you really had the time, you might want to mess with keybindings to make running those commands more convenient.

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i got the following message <No outputs have backlight property> – krishna Jan 26 '12 at 6:17
@krishna From your tag, I presume you are using Nvidia? I actually don't have an Nvidia machine, but can you get to Nvidia X Server settings? If you can, going under X Server Diplay configuration > X Server Color correction might help, according to link – math4tots Jan 27 '12 at 6:16

Try switching off Num Lock.

With my z570 xubuntu the brightness keys are without function if Num Lock is active. When i switch it off every thing works fine.

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Try the following and see if after a reboot your brightness keys are functional again. Edit etc/X11/xorg.conf and add the another line to the Device section: Option "RegistryDwords" "EnableBrightnessControl=1"

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there is no such file!! – krishna Jan 26 '12 at 6:15

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