How to turn On or Off Automatic Brightness Adjustment in Windows 7 or Windows 8
The brightness of monitors or laptop screens can be set to adjust automatically according to the ambiance light of the place you are sitting in, with your computer. This feature can be either automated or manulalized according to your needs. This feature is actively known with the name 'adaptive brightness'.
Adaptive brightness is a kind of technology that adjusts brightness for different kind of content that is shown on the display screen. It adapts to the environment and thus making displays dim or brighter. If you are viewing the darker content on the screen, the technology would dim the display and when doing typing work or viewing brighter content with white backgrounds, the display would increase the brightness automatically.
Read more: http://goo.gl/1wGl8L