[opendtv] Re: Why Europe should choose 720P for HDTV
- From: Terry Harvey <tjharvey@xxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sun, 12 Dec 2004 11:29:52 -0700
Tom,
I agree with what you say below. But following the context of John
Watkinson's excellent paper, what if we divorce ourselves from considering
spatial "image capture - transmission - display" as one? In the dismissive
argument made against Fox's 'upconverted' 480p, it seems the issue of
oversampling at the point of image capture has been ignored.
Have there been any practical demonstrations of what Watkinson has considered?
Terry Harvey
At 02:07 PM 12/11/2004 -0500, you wrote:
>For the 'real life' benefits of 1080i just read the AV Science Forum.
>The 1080i stations (all but Fox & ABC/Disney) seem to be generally rated
>as having a better picture. www.avsforum.com , but the site is down
>today and I can't provide links to the recent topics.
>
>I'm not sure I'm able to provide any really convincing theoretical
>arguments, though I'll mention one thing. See the paper on Craig's site
>on "An Increase of Vertical Resolution in Progressive Scanned Moving
>Images", at http://opendtv.org/Progressive.html .
>
>This paper talks about how our eyes can gather more detail from an image
>by tracking motion, considering multiple adjacent frames at a time. I
>believe we can also do this for interlaced images. So, either way, we
>pick up a bit more detail than the number of lines or pixels might suggest.
>
>Depending upon whether an image is moving (say) vertically at multiples
>of 0, .5, 1, 1.5, etc. lines / frame we may or may not be able glean
>extra detail from the series of video images since the pixels on
>adjacent frames may just more or less line up the those on the current
>frame, helping nothing. And images move in 2 dimensions, not just
>vertically so it gets a bit more complicated. But one possible advantage
>of interlace is that for the case of (close to) zero vertical motion we
>get the maximum amount of enhancement from this process. Compare this
>to progressive where the optimum values are .5, 1.5, etc.
>
>Now I believe zero motion is not only the most commonly occurring value
>but also the one where it is easiest for our eyes to track (non) motion
>and thus see more detail. This should give a small benefit to
>interlace, since it the worst case for progressive. I'm really only
>saying that interlaced still pictures have more resolution than moving
>pictures, which everyone knows. But it is still an advantage that can
>be used and seems to work well. The whole thing is a bit more
>complicated than that but it's the best I can explain it.
>
>I realize there are a number of compensating MPEG-2 and other drawbacks
>and a couple of popular studies that suggest interlace is a very bad
>thing. I'm sure many will now point them out again so I guess I don't
>have to.
>
>- Tom
>
>
>
>Terry Harvey wrote:
>
> > Tom,
> >
> > Please elaborate what you mean by 'theoretical' and 'real life' benefits?
> > Is not your statement non sequitur considering the earlier discussions in
> > this thread?
> >
> > Terry Harvey
> >
> >
> >
> >>Not withstanding, I've since started to see both the theoretical and
> >>obvious real life benefits of interlace and have changed my mind a bit
> >>about that issue. I'm not so sure that each successive frame should
> >>represent samples from the same location, which is what 'progressive' is
> >>all about.
> >>
> >>- Tom
> >
> >
> >
> >
> >
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