Re: Why interlaced HDTV?

In article <ddu455$9j8$1$8302bc10@xxxxxxxxxxxxxxxx>, Stephen wrote:
> > In a discussion today with a colleague I argued that it was illogical to
> > carry interlacing forward into the forthcoming HD standards. [snip]
> > The people who design these standards aren't stupid, so obviously I'm
> > missing something. Can anyone elucidate?
> >
> I think the main reason for interlace is that the higher number of lines
> sounds better and will sell better, just as a 3GHz computer processor will
> sell better than 2GHz, even if everything else about it is worse.

Surely you're joking?! All other things being equal, interlaced video looks
unquestionably better. Have you ever seen a 25Hz display? To transmit a
non-interlaced image with the same picture update rate as an interlaced one
(i.e. 50Hz), and the same number of lines in each picture (i.e. 575) you
would need twice the bandwidth. Vertical resolution affects picture sharpness
but picture update rate affects movement portrayal. Interlace is a clever way
of accommodating both requirements reasonably well without complex technology
and withoiut doubling the bandwidth requirement.

Converting video from one frame rate to another (something that wasn't
thought of when it was invented) is more complicated if it is interlaced,
which is why many advocates of new video standards are suggesting they should
not use interlace. Also, computer displays don't benefit from it because they
normally show static information and are used at a much smaller viewing
difference, and many people think that computer displays and television
displays ought to use the same standards.

I think it is the use of the word "progressive" which is used because it
"sounds better", because all it really means is "non-interlaced", and without
increasing the available bandwidth, the only "progress" it offers is towards
a less realistic portrayal of moving objects.

Rod.

.

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