Dell E2211H Monitor - Manual (Page 17)

Brightness / Contrast Use this menu to activate Brightness/Contrast adjustment.
Brightness Brightness adjusts the luminance of the backlight.
Press the button to increase brightness and Press the
NOTE: Brightness control will be greyed out during "Screen dim" in PowerNap option when screen saver is activated.
Contrast Adjust Brightness first, and then adjust Contrast only if further adjustment is necessary.
Press the button to increase contrast and
The Contrast function adjusts the degree of difference between darkness and lightness on the monitor screen.