ATIS Telecom Glossary
Thursday, April 24, 2014

A B C D E F G H I
J K L M N O P Q R
S T U V W X Y Z  
Go
 
Glossary Home
Foreword
Introduction
Normative References
Using the ATIS Telecom Glossary
Annex A: Informative References
 
 
 
<< Back
chroma keying
In television, nearly instantaneous switching between multiple video signals, based on the state, i.e., phase, of the color (chroma) signal of one, to form a single composite video signal. Note 1: Chroma keying is used to create an overlay effect in the final picture, e.g., to insert a false background, such as a weather map or scenic view, behind the principal subject being photographed. Note 2: The principal subject is photographed against a background having a single color or a relatively narrow range of colors, usually in the blue or green. When the phase of the chroma signal corresponds to the preprogrammed state or states associated with the background color, or range of colors, behind the principal subject, the signal from the alternate, i.e., false, background is inserted in the composite signal and presented at the output. When the phase of the chroma signal deviates from that associated with the background color(s) behind the principal subject, video associated with the principal subject is presented at the output. Synonyms color keying, [loosely] blue-screening, [in security] keying.

 

 

 

 

 

 

 

 

 

 



 
These definitions were prepared by ATIS Committee PRQC
 
For more information on the work related to these definitions,
please visit the ATIS website and the ATIS Document Center