Xref: utzoo comp.graphics:6946 rec.video:7553
Path: utzoo!utgpu!watmath!att!ulysses!ggs
From: ggs@ulysses.homer.nj.att.com (Griff Smith)
Newsgroups: comp.graphics,rec.video
Subject: Re: HDTV and ATV Glossary (TN32)
Summary: evils of frame duplication
Keywords: 525/59.94, 625/50, NTSC, PAL, SECAM, Component, Composite,
Message-ID: <12045@ulysses.homer.nj.att.com>
Date: 17 Aug 89 13:28:22 GMT
References: <120919@sun.Eng.Sun.COM> <121076@sun.Eng.Sun.COM> <428@ctycal.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 42

In article <428@ctycal.UUCP>, ingoldsb@ctycal.COM (Terry Ingoldsby) writes:
> In article <12027@ulysses.homer.nj.att.com>, ggs@ulysses.homer.nj.att.com (Griff Smith) writes:
> > I assume this is part of the attempt to get rid of interlace so the
> > computer graphics folks can avoid motion artifacts.
> > ...  What is so evil about interlace?
> > 
> Interlace can be a real pain if you want to draw thin horizontal lines, or
> diagonal lines that cause only a single pixel to be illuminated on a scan
> line.  In these cases the refresh rate is only the frame rate (eg. 30 Hz),
> not the field rate, and flicker becomes quite annoying.  You can
> occasionally see this on poorly designed text overlaid during TV sports
> programs.  The flicker can be very visible.
> -- 
>   Terry Ingoldsby                       ctycal!ingoldsb@calgary.UUCP
>   Land Information Systems                           or
>   The City of Calgary         ...{alberta,ubc-cs,utai}!calgary!ctycal!ingoldsb

I don't think I've ever noticed this.  If this is the kind of argument
that is being used, I think the industry is putting something over on
us.  I HAVE noticed the following:
to
1) When watching film on TV, pans get doubled (probably also tripled)
images because the stationary images get frozen on my retina while I
try to follow the apparent motion.  If a 24 fps HDTV standard is
adopted, with triple scanning of frames, I'm going to see tripled
images any time the image pans.

2) When watching film on film, pans are horribly blurred because the
image DOESN'T get frozen on my retina while I follow the apparent
motion.  IMAX is just as bad as the others.  Does anyone know of
attempts to build strobed theater projection systems that avoid this
problem?

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?
-- 
Griff Smith	AT&T (Bell Laboratories), Murray Hill
Phone:		1-201-582-7736
UUCP:		{most AT&T sites}!ulysses!ggs
Internet:	ggs@ulysses.att.com