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From: john@datacube.UUCP
Newsgroups: comp.graphics
Subject: Re: Broadcast Digital Video Effects
Message-ID: <102300003@datacube>
Date: Thu, 2-Jul-87 00:20:00 EDT
Article-I.D.: datacube.102300003
Posted: Thu Jul  2 00:20:00 1987
Date-Received: Sat, 4-Jul-87 05:51:12 EDT
References: <222@sugar.UUCP>
Lines: 32
Nf-ID: #R:sugar.UUCP:-22200:datacube:102300003:000:1407
Nf-From: datacube.UUCP!john    Jul  2 00:20:00 1987


> Written  8:22 pm  Jun 25, 1987 by karl@sugar.UUCP in comp.graphics */
> ---------- "Broadcast Digital Video Effects" ---------- */
>
>... but the ultimate chroma keyer is called UltiMatte (TM).  It's
>digital and smart, so its keys don't leave those annoying edges around the
>weatherman and glitches in his hair when he's in front of the blue screen.
>.....
>bbs:  (713) 933-2440	voice: (713) 933-9134

I believe you are incorrect about  the UltiMatte.   It  is a strictly
analog beast.  

As  I  recall  the  unit croma  keys an  RGB source  over another RGB
source.    It  can  also key  a composite  source (NTSC  or PAL) over
another composite, but to do this it requires RGB  for the forground.
It uses the  RGB from  the forground  to develop  an analog "Keyhole"
signal.  I believe the key  signal is  proportional to  the amount of
blue in the signal where there is no green or  red present.   The key
signal is then multiplyed against the background to  make the cutout.
The  key  signal  is  also  subtracted from  the blue  channel on the
foreground, removing the unwanted blue background  from the forground
image.  The processed forground and background are  then simply added
together to make the final image.  

				John Bloomfield

Datacube Inc. 4 Dearborn Rd. Peabody, Ma 01960 	617-535-6644
	
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