Dell IN1930 Monitor - Manual (Page 17)

Brightness Allows you to adjust the brightness or luminance of the backlight.
Press the key to increase brightness and press the key to decrease brightness (min 0 ~ max 100).
Contrast Allows you to adjust the contrast or the degree of difference between darkness and lightness on the monitor screen. Adjust brightness first,
and adjust contrast only if you need further adjustment.
Press the key to increase contrast and press the key to decrease contrast (min 0 ~ max 100).