Well, what i meant was i need to change screen brightness, the brightness that you change to make battery last longer.. not change gamma.!
I wrote backlight brightness because in every sample and forum that i was searching for, under "screen brightness" there was no sample that actuali affected the brightness, only gamma and contrast.! and with changeing gamma and contrast to lower, when i press "decrase brightness" button on my keyboard, it makes the brightness lower.. so its not the same thing, as that gamma, contrast thing..
Hope you understand now, what i need..