Black level
Encyclopedia
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).
The voltage of the black level varies across different television standards. PAL
sets the black level the same as the blanking level, whilst NTSC
sets the black level approximately 54 mv above the blanking level.
User misadjustment of black level on monitors is common. It results in darker colours having their hue changed, it affects contrast, and in many cases causes some of the image detail to be lost.
Black level is set by displaying a testcard image and adjusting display controls. With CRT displays:
In Digital video
black level usually means the range of RGB values in video signal, which can be either [0..255] (typical of a computer output) or [16..235] (standard for video).
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
black level is defined as the level of brightness at the darkest (black) part of a visual image or the level of brightness
Brightness
Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target...
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
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
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).
The voltage of the black level varies across different television standards. PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
sets the black level the same as the blanking level, whilst NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
sets the black level approximately 54 mv above the blanking level.
User misadjustment of black level on monitors is common. It results in darker colours having their hue changed, it affects contrast, and in many cases causes some of the image detail to be lost.
Black level is set by displaying a testcard image and adjusting display controls. With CRT displays:
- 'brightness' adjusts black level
- 'contrast' adjusts white level
- CRTs tend to have some interdependence of controls, so a control sometimes need adjustment more than once.
In Digital video
Digital video
Digital video is a type of digital recording system that works by using a digital rather than an analog video signal.The terms camera, video camera, and camcorder are used interchangeably in this article.- History :...
black level usually means the range of RGB values in video signal, which can be either [0..255] (typical of a computer output) or [16..235] (standard for video).
See also
- Picture line-up generation equipmentPicture line-up generation equipmentIn television, picture line-up generation equipment is equipment used to generate greyscale test patterns in order to adjust the black level and contrast of a picture monitor...
(PLUGE)