Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!amdcad!ames!ll-xn!mit-eddie!uw-beaver!cornell!rochester!PT.CS.CMU.EDU!SPEECH1.CS.CMU.EDU!phd
From: phd@SPEECH1.CS.CMU.EDU (Paul Dietz)
Newsgroups: comp.sys.mac
Subject: Re: SCREENS HURT EYES (Mac SE, Plus)
Message-ID: <893@PT.CS.CMU.EDU>
Date: 18 Feb 88 16:47:22 GMT
References: <1767@batcomputer.tn.cornell.edu> <993@ski.UUCP> <3645@batcomputer.tn.cornell.edu> <3402@sphinx.uchicago.edu> <699@pasteur.Berkeley.Edu> <3720@ihlpf.ATT.COM>
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Organization: Carnegie-Mellon University, CS/RI
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Keywords: screens, screen, hurt, eyes, Clinton Taiwan Corp.

In article <3720@ihlpf.ATT.COM> straka@ihlpf.UUCP (55223-Straka,R.J.) writes:
>Higher brightness levels naturally increase the perceived flicker
>on the display.

I wasn't too sure about this statement, so I decided to do some checking.
According to Cornsweet, "Visual Perception", for high frequencies

	"what determines wether or not the the fluctuation will be seen
	is the absolute amplitude of the flucuation, not the level around
	which it is fluctuating."

If the phosphur is fairly linear, then the original statement is absolutely
correct. However, if it saturates, it could well be that there is a
brightness level which is maximally bad, and either increasing, or
decreasing the brightness would help. Does anybody out there know anything
about the physics of CRT's?

Paul H. Dietz                                        ____          ____
Dept. of Electrical and Computer Engineering        / oo \        <_<\\\
Carnegie Mellon University                        /|  \/  |\        \\ \\
--------------------------------------------     | | (  ) | |       | ||\\
"If God had meant for penguins to fly,             -->--<--        / / |\\\  /
he would have given them wings."            _________^__^_________/ / / \\\\-