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Ms. Masucci and Chroma
- To: 'telecine internet group' <telecine at alegria.com>
- Subject: Ms. Masucci and Chroma
- From: Jon Walley <jonw at tvp.co.uk>
- Date: Fri, 31 Oct 1997 11:19:14 -0000
- Encoding: 51 TEXT
- Resent-Date: Fri, 31 Oct 1997 03:26:32 -0800
- Resent-From: telecine at sun.alegria.com
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Anne Masucci wrote
* " My first question is, has anyone used a lightning display for
color correction, and if so, do you prefer it to the "traditional"
vector and waveform, and why? Also, how do I know when I have illegal
chroma in the video? Is is when the color goes outside the boxes?"
As I understand it, Lightning Displays can show INVALID chroma - Chroma
that lies outside the component chromaticity envelope.
Vectorscopes can display chroma that is ILLEGAL - Chroma that is outside
the parameters of the coded system i.e. PAL or NTSC
Can anyone tell me how US colourists calibrate their vectorscopes using
only 75% SMPTE bars ? Is there still a limit to how much chroma can
tolerated on the broadcast sytem ? I have never seen an NTSC vectorscope
with a 100% graticule.
* "Speaking of illegal chroma, this leads me to my next question. So
I've had three different answers on this one. Maybe someone can
the diffinitive answer. When looking at the vector, when is the
illegal? I always thought it is illegal when it goes beyond the
boxes. Then I was told that chroma is illegal if it goes outside
Anne see my question above. If you calibrate your vectorscope with SMPTE
bars with 75% Chroma then the chroma can go outside the boxes but you
have no measurement of value - it's more than 75% - you can't say how
much more. If you have Bars direct from your Telecine what levels are
they and what are you measuring them with ?
* "Today I was told that chroma is illegal if it goes outside the
big boxes (which, of course, are outside the little ones). (Like
technical terms?) I also go by the rule that if chroma goes
120ire on the waveform monitor, then it is illegal too."
Could someone advise what overall NTSC levels are permissible ?
No black below 7.5 IRE - No white over 100 IRE - OK that covers
Luminance in NTSC.
But what about Chroma levels ?
thanks to Rich Zabel of Tekniche for support of the TIG in 1997
TIG subscriber count is 884 on Fri Oct 31 03:26:14 PST 1997
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