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I have a Sony T-Series notebook with an Intel HD 4000 graphics card. I use Ubuntu 12.04. The brightness control of the screen does not work (doesn't matter if I do it with the keyboard or in the system settings). I see the bar that is changing but nothing happens.

merged by Luis Alvarado May 4 '13 at 12:18

This question was merged with How to control Brightness because it is an exact duplicate of that question.

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