Xref: utzoo comp.graphics:6955 rec.video:7557
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From: dya@unccvax.UUCP (York David Anthony @ WKTD, Wilmington, NC)
Newsgroups: comp.graphics,rec.video
Subject: Re: HDTV and ATV Glossary (TN32)
Keywords: 525/59.94, 625/50, NTSC, PAL, SECAM, Component, Composite,
Message-ID: <1612@unccvax.UUCP>
Date: 17 Aug 89 17:59:54 GMT
References: <120919@sun.Eng.Sun.COM> <121076@sun.Eng.Sun.COM> <428@ctycal.UUCP> <12045@ulysses.homer.nj.att.com>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 30

In article <12045@ulysses.homer.nj.att.com>, ggs@ulysses.homer.nj.att.com (Griff Smith) writes:

> Interlace seems to be an excellent way to cut the bandwidth in half
> while avoiding flicker and motion artifacts.  Other than pressure
> from the movie industry, what are the other arguments for eliminating
> interlace?

	1. Interlace causes a line crawl artifact which is extremely
obvious and highly annoying.

	2. Interlace lowers the vertical resolution for a given number
of TV lines.  This is principally due to intratarget leakage in tube
type cameras, and the precharge/decay time characteristics of the
CRT phosphour.  ("Deinterlacing" by using a long persistance phosphour
works, but screws up motion royally.)

	3. Interlace requires the ability to retrigger the vertical
oscillator with much greater precision than progressive scan, in
order that the "odd" lines fall exactly inside the "even" lines;

	4. Odd/even field housekeeping can sometimes be a pain in
the butt when it comes to designing things like time base correctors
and such.  Why bother?

	Yes, interlacing does save approximately half the bandwidth,
but it also cuts the information content in the diagonal and vertical
domain.

York David Anthony
BPH-880505OT (WRPL) Wadesboro, NC