BLACK LEVEL

Video 'black level' is defined as the level of brightness at the darkest (black) part of a visual image or the level of [brightness] at which no light is emitted from a screen, resulting in a pure black screen.
Video displays generally need to be calibrated so that the displayed black is true to the black information in the [video] signal. If the black level is not correctly adjusted visual information in a video signal could be displayed as black, or black information could be displayed as above black information (gray).
See also Pluge.