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From: bcw@rti.rti.org (Bruce Wright)
Newsgroups: comp.windows.ms
Subject: Re: Interlaced monitors
Summary: Flicker and response
Message-ID: <1991Mar15.023840.28733@rti.rti.org>
Date: 15 Mar 91 02:38:40 GMT
References: <6919@mace.cc.purdue.edu> <1991Mar6.174932.14469@cbnews.att.com> <70457004@bfmny0.BFM.COM>
Organization: Research Triangle Institute, RTP, NC
Lines: 42

In article <70457004@bfmny0.BFM.COM>, tneff@bfmny0.BFM.COM (Tom Neff) writes:
> In article <27D66A39.5235@maccs.dcss.mcmaster.ca> riehm@maccs.dcss.mcmaster.ca (Carl Riehm) writes:
> >                              The other may be that flicker
> >is noticeable to some people and not to others, at least that was mentioned 
> >recently in an article in PC Magazine (I think it was PCMag..).
> >Carl Riehm.
> 
> Good old PC magazine... home of the half baked theory. :-)  I'll wager
> that given the same screen and image, nearly everyone notices interlace
> to the same degree.

I wouldn't endorse everything that's said in PC Magazine, but I
think the notion that different people react differently to screen
interlace probably has some truth in it.

A number of years ago when I worked with some medical imaging
hardware, I made the comment that some manufacturer's hardware
had more of a visible flicker problem than others, and that I
could see the flicker with a couple of the monitors even when
I looked directly at the screen (the cones in the center of the
human visual field have a longer response time than the rods at
the edges and therefore flicker is less noticeable when you look
directly at the monitor than if you look somewhat away from it).
Turned out I was about the only one in the lab who could see the 
flicker on those monitors unless the others looked at the monitors
"out of the corners of their eyes" when they could see it too.

We didn't attempt to do a controlled study, but I suspect that
there is a significant difference between individuals either in 
basic visual perception or in the psychological reaction to the
stimulus.  It doesn't particularly matter which as far as the
reaction goes - it bothered some people much more than others.

It will also matter what kind of lighting is going to be around 
the monitor - florescent lighting is going to be worse because it
also has a "flicker" that will resonate with the flicker in the
screen to make the observed flicker much greater.

It's a good idea to see the monitor in action in something close
to its ultimate environment to see what it will look like to _you_.

						Bruce C. Wright