Windows Phone 8 enables you to
adjust the brightness of the screen either automatically (in response
to the current lighting conditions) or manually to a level of your
choosing.
Automatically Adjusting the Screen Brightness
Windows Phone 8 can automatically adjust the
screen’s brightness based on the current lighting conditions. If you
want the phone to adjust the screen’s brightness automatically, go to
the Settings screen and perform these steps:
1. Scroll through the list of settings and tap Brightness.
2. Set the Automatically Adjust slide bar to On.
