[Tig] SMPTE Bars/Testing

Steven Bradford SBradford at collinscollege.edu
Mon Apr 2 18:43:48 BST 2007


 >>What are those black bars at the bottom of the pattern stand for?
there are total 8 black bars in the pattern, 5 of them are at the
bottom, right?

These are for setting the black level (or pedestal) on NTSC monitors.
That standard black level (The largest blocks at the bottom, are at 7.5
IRE.
The other two stripes are just below and just above 7.5 on a waveform
monitor. 4 IRE and 10 IRE.
The black level (or brightness) control is adjusted so the 4 IRE stripe
just disappears into the 7.5 black surround, and the 10 IRE stripe is
just barely visible against the 7.5 black surrounds.

>>And why SMPTE Bars pay more attention on the black or grey color, less
on the white or brighter part of the motion pictures?

This one I can't answer for sure, I'd just hazard a guess. But both
these controls are highly dependent on ambient room light, and should be
set in the room illumination level that you'll be using the monitor in.

Steven Bradford
Collins College
Tempe Arizona




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