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Posted by Joshua Zyber on 01/17/07 13:21
"M.I.5" <no.one@no.where.NO_SPAM.co.uk> wrote in message
news:45add5bc$1_1@glkas0286.greenlnk.net...
> Your choice of wording is suggesting to me that it is you who doesn't
> really quite appreciate what is going on here.
Funny, that's exactly what I've been saying about you all along.
> I think you (and many
> others here) have assumed that when you play a 720 x 576 DVD source
> into a 720 x 576 LCD or Plasma display device, that the pixels are
> mapped on a 1:1 basis. This just doesn't happen. The DVD is
> converted to the analogue domain and sent to the display as a CVBS,
> S-Video, RGB or YCBCR analogue signal (the last two giving by far the
> best display).
Modern HDTVs have digital HDMI connections that avoid the conversion to
analog.
> The display then maps the analogue signal back to a
> digital granularity in the X and Y axis (though retains the analogue
> in the Z axis). There is nothing in the analogue signal that allows
> the display to map the original pixels 1:1. It might be close, except
> that displays usually lose the outer parts of the picture (overscan).
> The use of displays with larger numbers of pixels that are available
> in the consumer market still are not an integral multiple of the
> original source, but the finer granularity allows a better
> interpolation of what is contained in the analogue video.
So then you admit that any added pixels are interpolated, not real
detail found in the original source?
> And the pixels on most displays aren't square either. And that phrase
> 'directly mapped' tells me that haven't got it. See above.
I'll remind you that you're the one who came up with the ridiculous
1440x1152 claim, not me. I've never claimed that the displays contained
an even multiplier of the source pixels. I'm trying to debunk your claim
that such is necessary.
> Some newer DVD players now feature HDMI (digital) interfaces, but as
> these are used with HD ready displays, a 1:1 correspondence still does
> not occur.
Of course not. DVD pixels aren't square, but the display's pixels are.
Further, HD displays have much higher pixel counts than a DVD source.
There will never be a direct 1:1 correspondence. Interpolation will
always be necessary for those reasons. But that doesn't mean that only a
1440x1152 display can capture DVD resolution. Watching a Standard
Definition DVD on a higher resolution screen requires scaling.
Interpolated pixels are not found in the source, obviously.
>> Where did you even come up with this ridiculous 1:2 ratio between DVD
>> resolution and display pixels? Do you not realize that DVD pixels
>> aren't square? A 720x576 DVD image directly 1:2 mapped to a 1440x1152
>> would give you a picture in the wrong shape!
>
> And the pixels on most displays aren't square either.
The only digital displays that use non-square pixels are plasmas. LCD,
DLP, and LCOS/D-ILA all use square pixels.
>> And puzzle this over, smarty pants: If a meager DVD really requires a
>> 1440x1152 display to resolve it, wouldn't that also mean that a true
>> High Definition image would require 3840x2160 pixels? So does that
>> mean that all of the HDTVs out there aren't really capable of
>> displaying HD content at all? And by the same logic, an HD signal on
>> a current "HDTV" screen would show no improvement over a DVD, which
>> is already barely taking advantage of the screen?
>
> The current crop of HD displays are caoable of displaying an HD image.
> They are just not capable of displaying it as well as they could,
> especially given that the pixel resolution of displays in the consumer
> market does not exactly match any of the recognised HD formats.
720p, 1080i, and 1080p are not recognized HD formats anymore? When did
that happen?
Do you own an HDTV? Have you even seen one in person? It certainly
sounds as if you've never tried watching both DVD and HD content on one,
or you would understand the difference.
>> Ludicrous. Simply ludicrous.
>
> I suggest you research the issue, and once you see the flaws in your
> arguments, it may all start to make sense.
I suggest you do the same. Your claims about DVDs requiring a 1440x1152
display are absurd to say the least.
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