[opendtv] Re: France bids farewell to SECAM

  • From: Olivier Houot <olho_avatar_i@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Thu, 15 Dec 2011 23:05:37 +0100

Mark shubin wrote:
> Well, you need to change one (the burst or the subcarrier in the 
> picture) relative to the other.  It's a routine operation for
> processing 
> amplifiers (proc amps).
> 

So you can achieve both phase and amplitude modification by touching the
burst, as it is outside the modulated part of the video line (at the
price of potential non compliance)? Or, for amplitude would you try a
comb filter with adjustable gain ?

But i think i used an incorrect word when i asked my question about
color correction. To you it probably means : to compensate for any
unintended drift in chroma that would have occurred during processing.

But perhaps i should have said: color modification. In component you
would have the capability to tweak the amount of red, green or blue
primaries at will. But in the modulated signal you would have to adjust
independently the luma (which mostly contains green but still has an
amount of red and blue components) R-Y and B-Y, so you would have to
compute a modification of those three that achieves the correct
primaries ratio, despite their relationships, and apply them to each
targetted part of the signal despite the fact they are all mixed
together in the composite signal. It does not seem reasonable, so i
suppose for this you do have to demodulate.

Or would you say this kind of color modification is not needed very
often in the profession anyway?

 
 
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