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From: skinner@saber.UUCP (Robert Skinner)
Newsgroups: net.micro.amiga
Subject: Re: on interlace
Message-ID: <1767@saber.UUCP>
Date: Fri, 13-Sep-85 13:59:44 EDT
Article-I.D.: saber.1767
Posted: Fri Sep 13 13:59:44 1985
Date-Received: Sun, 15-Sep-85 04:56:57 EDT
References: <3629@topaz.RUTGERS.EDU>
Organization: Saber Technology, San Jose, CA
Lines: 50

> From: keithe%tekgvs%tektronix.csnet@csnet-relay.arpa
> 
> 
> >> I can't figure out what an interlaced monitor is.
> >> What will look better in the Amiga: 640x400, or
> >> 640x200? Does it matter?
> 
> >The price one pays is flicker, since screen sweeps are only done 30
> >times a second, as opposed to 60 times a second during non-interlace.
> >Thus a higher persistance monitor is needed to eliminate flicker.
> 
> Well, not really... One of the *advantages* of interlace is that
> flicker is reduced. A "half" frame is generated every 1/60 of a second,
> but that half-frame is distributed over the entire face of the crt.
> Then, 1/60th of a second later, the intervening lines are drawn for the
> other half of the frame. (P.S., each half-frame is referred to as a
> "field.") So the eye thinks it's getting refreshed 60 times every
> second  - because it can't distinguish the separate lines - instead of
> at a 30 per second, which would be very noticeably flickering.
> 
> Keith Ericson  at TekLabs (resident factious factotum)
> Tektronix, PO 500, MS 58-383
> Beaverton OR 97077
> (503)627-6042
> uucp:	 [ucbvax|decvax|ihnp4|(and_many_others)]!tektronix!tekgvs!keithe
> CSnet:	 keithe@tek
> ARPAnet: keithe.tek@rand-relay

NO, NO, NO!!  If you draw a lone horizontal line on the screen, it
*will* flicker, because it is only refreshed 30 times a second.  Even
if you are thinking about large painted areas it doen't work.  The two 
fields are (ideally) displaced by the size of a scan-line (Or you
don't actually get the required resolution).  This usually results in
a lower overall intensity, unless you have very long persistence
phosphor.  But very long persistence phosphor "streaks" when you try
to do dynamic frames, i.e. real-time graphics.

You're not in the monitor or graphics design groups are you?

Non-interlaced Forever...

------------------------------------------------------------------------------
			.. man then went on to prove that black was white, 
			and was promptly killed at the next zebra crossing.

Name:	Robert Skinner
Snail:	Saber Technology, 2381 Bering Drive, San Jose, California 95131
AT&T:	(408) 945-0518, or 945-9600 (mesg. only)
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