Dell U2913WM manual Contrast, Auto Adjust

Icon Menu and	Description
Submenus
Brightness/Contrast Use this menu to activate Brightness/Contrast adjustment.

Brightness	Brightness adjusts the luminance of the backlight.
	Push the	button to increase brightness and push the	button to decrease brightness (min 0 ~ max 100).
Contrast	Adjust Brightness first, and then adjust Contrast only if further adjustment is necessary.
	Push the	button to increase contrast and push the	button to decrease contrast (min 0 ~ max 100).
	The Contrast function adjusts the degree of difference between darkness and lightness on the monitor screen.
Auto Adjust	Even though your computer recognizes your monitor on startup, the Auto Adjustment function optimizes the display settings for use with
	your particular setup.

Auto Adjustment allows the monitor to self-adjust to the incoming video signal. After using Auto Adjustment, you can further tune your monitor by using the Pixel Clock (Coarse) and Phase (Fine) controls under Image Settings.