[opendtv] Re: De-interlacing with HQV high quality video processing
- From: Olivier Houot <olho_avatar_i@xxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sat, 08 Oct 2005 00:34:35 +0200
Jeroen wrote :
> For emissive displays it is relatively easier to just blank
> half of the lines and thus obtain an interlaced raster. It does
> not necessarily degrade the efficiency, but it will degrade the
> peak light output power by 50% (i.e. less "sparkle").
>
I thought it was perfectly acceptable to run a LED, for example, at
twice its rated current, provided it is switched on at a duty rate of
50%, which averages out to the rated current. Wouldn't that solve your
problem of reduced light ouput power ?
> Right, and there is the bigger catch: (vertical) scaling can
> ONLY be done on de-interlaced signals. So in practice de-
> interlacing is always necessary. And then you might as well
> send it to a progressive display. Unless you have a display
> that performs better in interlaced mode (CRT, ALiS), then at
> the end you would convert the signal back to interlaced again.
>
So it seems the universal HDTV display should be exactly 1080 lines
vertically, no more, no less, as this is the only way to avoid scaling
of interlaced signal. 720p, being progressive, can easily be scaled to
1920x1080, and displayed as either interlaced or progressive, depending
on display capability. In that regard, the 1024 lines resolution of the
ALIS seems to be a particularly bad choice, considering the specificity
of that technology.
However it would not be possible to take advantage of a x2 oversampling
display without compromising interlace. According to some recent news,
this may become a significant drawback in a not so distant future
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