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Re: Screen Flicker Test

From: David Woolley <david@djwhome.demon.co.uk>
Date: Tue, 1 Mar 2005 22:54:25 +0000 (GMT)
Message-Id: <200503012254.j21MsP701428@djwhome.demon.co.uk>
To: w3c-wai-ig@w3.org

> 2 and 55 Hz?  I saw somewhere that you could use a stop watch but I

2 should be obvious.  Most European TV sets will flicker at 50Hz (some
upmarket ones now memorise the whole frame and scan it out 100 Hz).
Some display modes on multi-sync monitors will be below 55 as well.
Basically this upper limit is going to be violated by the user's choice
(or rather their supplier's choice) of hardware.

Also, anything even vaguely close to 55 Hz will strobe against it, and
produce an unattractive result even for people who are not flicker
sensitive.  I'd therefore seriously question whether the person who set
the 55 Hz limit actually understands how CRT displays work.

Actually, from my point of view, the worst flicker effects I've seen
won't be obvious to many people testing as they only happen in interlaced
display modes (the result of not wasting natural resources by replacing
a perfectly useable SVGA monitor with a multi-sync one).  It happens when
designers use patterns with alternate scan lines dark and light.
Received on Tuesday, 1 March 2005 22:55:27 GMT

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