LG 34GP83A Owner's Manual page 26

26
Black Level
Picture Adjust
DFC
Picture Reset
Sets the offset level (for HDMI only).
y Offset: as a reference for a video signal, this is the darkest color the monitor can display.
High Keeps the current contrast ratio of the screen.
Low
Lowers the black levels and raises the white levels from the current contrast ratio of the screen.
On Adjusts the brightness automatically according to the screen.
Off Disables the DFC feature.
No Cancel the select.
Yes Returns to the default settings.