Dell UltraSharp UP3221Q User Manual page 49

Reset Color Reset your monitor color settings to the factory
settings.
Luminance Luminance adjusts the luminance of the backlight.
Toggle the Joystick up to increase the luminance and
toggle the Joystick down to decrease the luminance 
(min. 45 / max. 350).
NOTE: Changes made in Luminance menu will not be
saved in the preset color space.
NOTE: Luminance is grayed out when Color Space is
set to CAL 1 or CAL 2.
│
Operating the Monitor 49