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RE: guideline 7.1 about screen flickering (fwd)

From: Gregg Vanderheiden <gv@trace.wisc.edu>
Date: Wed, 25 Jul 2001 00:30:44 -0500
To: "'Charles McCathieNevile'" <charles@w3.org>, "'WAI GL'" <w3c-wai-gl@w3.org>
Message-ID: <001101c114ca$f7d58740$b2176880@trace.wisc.edu>
The guideline doesn’t bar movement between 5 and 50 hZ.  It only bars
flicker.   This image doesn’t flicker on my screen. Does it on anyone

It is annoying -- and distracting -- but it doesn’t trigger the epilepsy
guideline unless if flashes.

Don’t know about distraction - that is another guideline
 -  (doesn’t stop when I  turn of images)


-- ------------------------------
Gregg C Vanderheiden Ph.D.
Professor - Human Factors
Dept of Ind. Engr. - U of Wis.
Director - Trace R & D Center
Gv@trace.wisc.edu <mailto:Gv@trace.wisc.edu>, <http://trace.wisc.edu/>
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-----Original Message-----
From: w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org] On
Behalf Of Charles McCathieNevile
Sent: Tuesday, July 24, 2001 1:38 PM
Subject: RE: guideline 7.1 about screen flickering (fwd)

I don't think that this image is OK, unless the group feels that the
user agents" part of the checkpoint means it is no onger applicable. It
at something between 5 and 25 Hz in my viewer, and may preset problems
concentration or photosensitive epilepsy.

I think that most browsers now allow people to stop the animation, but I
not think I am in a position to decide that for the group. Could we
add it to the agenda as a matter of some urgency.


Charles McCN

Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61
409 134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI    fax: +1
617 258 5999
Location: 21 Mitchell street FOOTSCRAY Vic 3011, Australia
(or W3C INRIA, Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex,

---------- Forwarded message ----------
Date: Tue, 24 Jul 2001 11:33:13 -0400
From: "Fitzgerald, Jimmie" <Jimmie.Fitzgerald@jbosc.ksc.nasa.gov>
To: 'Terrie King' <tking@ucp.org>, w3c-wai-ig@w3.org
Subject: RE: guideline 7.1 about screen flickering
Resent-Date: Tue, 24 Jul 2001 11:37:35 -0400 (EDT)
Resent-From: w3c-wai-ig@w3.org

Looks fine to me.  It isn't flickering at all.  What 'they' call screen
flicker is more in the lines of image changeouts and color changing.
really need to change their wording to 'element flicker' or something.
calling it screen flicker, I think monitor refresh rates.  And that is
something we as developers cannot control.

Your .gif is good to go.

Jim Fitzgerald

-----Original Message-----
From: Terrie King [mailto:tking@ucp.org]
Sent: Tuesday, July 24, 2001 10:45 AM
To: w3c-wai-ig@w3.org
Subject: guideline 7.1 about screen flickering

Okay, experts!  I have been asked to put another agency's animated gif
on my
Web site.  I am hesitant to  use it because of guideline 7.1--"Until
agents allow users to control flickering, avoid causing the screen to
flicker."  Here's the link to the checklist item:

How can I determine if the gif in question is within the guidelines?
attached)  If it is not, I guess I can ask for a non-animated gif.


Terrie L. King
Internet Marketing Manager

UCP National
1660 L Street, NW, Suite 700
Washington, DC  20036
Ph: 800-872-5827
Fax: 202-776-0414
Web site:  http://www.ucp.org
Received on Wednesday, 25 July 2001 01:36:37 UTC

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