screen brightness reduction software?

i'm a total new user of ubuntu. I use ubuntu 12.04 and my laptop is DELL studio 1558. the problem is the, the minimum brightness in my laptop is still pretty bright when using the computer in dark situation. Now i've tried tints, but i want a software that actually reduces the screen brightness. There's this app called 'dimmer' for windows which was perfect for me. But I don't seem to find its linux alternative. Any suggestion?

Try Redshift

Redshift adjusts the color temperature of your screen according to your surroundings. This may help your eyes hurt less if you are working in front of the screen at night.

To install Redshift, Redshift

There is a GUI version of Redshift that you can download.

^{Source:Redshift}

Try this in terminal:

xrandr --output LVDS1 --brightness 0.9

You can change the last value as you like, eg. 0.2