Can I adjust the Brightness settings of the touch screen on my Samsung Windows 8 Phone?
You can adjust the brightness level of your phone's screen.
Adjust Screen Brightness
Flick left to the Apps list from the Start screen and tap Settings > brightness. To manually adjust the brightness, tap the slider to turn the Automatically adjust feature off. Adjust the brightness level to your desired setting by tapping the Level box. Setting the brightness level manually can induce the phone to consume more battery power than if you use the Automatically adjust feature.