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Re: Clippers





Tony Meerakker wrote:

> In the NTSC composite world, we found ourselves pushing the envelope
> by adjusting the whites to 104 / 106 and the blacks down to between 7.5 to 3 units.
> In the component world these levels equate to signal levels of up to 725 /
> 730 mV and as low as 0 to -40mV.  What I get out of the SMPTE
> standard appears to suggest that video should stay between the 0 to
> 700mV range.  What happened to the headroom we used to play with?
>
> Any feedback would be appreciated

Greetings Tony,

Long time no see.  Aside from the luminance componant, remember that
composite NTSC encoding (or Pal, for that matter) does actually allow
for the reproduction of values that can produce higher than 100 IRE, or
700mv. of RG&B video levels from within the peak-to-peak "100%
modulated chroma" parameters.  In other words, in the composite domain,
yellows and cyans, for instance can produce RGB levels higher than 100 IRE
with a higher contribution of Y component.  Blues may also exceed 100
IRE if the Y contribution is higher than 11% IRE.  All this really means
though is that the monitor will produce a broader RGB output not restricted
within 700 IRE translating into brightness.  This amount of headroom should
not be a problem with present day monitors appropriately calibrated.   These
levels should also be well within the YUV parameters without requiring
clipping.

Regards,


Mike


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