[Tig] Combined measurement of Luminance plus Chrominance

Ken Miller kmiller
Wed Oct 23 20:43:30 BST 2002

Thanks to Dave and Bill for the technical reasons for limiting p/p 
luminance plus chrominance. Again thanks to Bill for debunking "vector 
chroma" as some standard to evaluate chroma levels.   I would like to 
add that in the DC area facilities, combined levels are kept to 110 IRE 
(770mv) for most broadcasters with a strict 100 IRE (700mv) for 
luminance. PBS technically accepts 120 IRE but prefers a lower figure. 
 For DTV delivery the norm is to monitor transcoded  YBR to RGB and keep 
a strict 0 to 100 IRE levels.  It doesn't work for dual delivery 
(analog/ DTV) so we use a "legalizer", for  both RGB and encoded video 
to control excessive chroma.  Most of the rest of the world wants the 
combined levels kept to 770mv.  

Ken Miller
Facility Manager
Henninger Video
Arlington, VA

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