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RE: guideline 7.1 about screen flickering (fwd)

From: Gregg Vanderheiden <gv@trace.wisc.edu>
Date: Wed, 25 Jul 2001 08:08:43 -0500
To: "'Anne Pemberton'" <apembert@erols.com>, "'Charles McCathieNevile'" <charles@w3.org>, "'WAI GL'" <w3c-wai-gl@w3.org>
Message-ID: <002901c1150b$36f47ae0$b2176880@trace.wisc.edu>
Hi Anne


You wrote:
" Let not forget that at present, there have been no actual
photo-epileptic seizures caused by anything transmitted on a computer
screen - only on a TV screen."

Has someone researched and found this?    Or is it just what we have
heard.  I would surprise me greatly.

By the way,  the problem in Japan was caused by computer generated
graphics (cartoon) I believe -- though it was on TV.   And from what I
understand it was intended to flash like that as you viewed it and it
was very bright flashing.   (It was a special "effect")

Anyone have any further info on this?

Gregg

-- ------------------------------
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/>
FAX 608/262-8848 
For a list of our listserves send “lists” to listproc@trace.wisc.edu
<mailto:listproc@trace.wisc.edu>


-----Original Message-----
From: w3c-wai-gl-request@w3.org [mailto:w3c-wai-gl-request@w3.org] On
Behalf Of Anne Pemberton
Sent: Tuesday, July 24, 2001 6:13 AM
To: gv@trace.wisc.edu; 'Charles McCathieNevile'; 'WAI GL'
Subject: RE: guideline 7.1 about screen flickering (fwd)

Greg,

         I agree that this image seems quite usable, and should not
trigger
any guidelines. The movement is well within the "safe" limits.  It is no

more (or less) annoying than other gif's used on the web. The movement
stopped when I used the Stop button in IE.

         It would be tragic if the guidelines were invoked so as to
prevent
use of movement and/or creative arts on the web.  Let not forget that at

present, there have been no actual photo-epileptic seizures caused by
anything transmitted on a computer screen - only on a TV screen. How
much
can we disturb the normal development of the web with a possibility?

                                                         Anne

At 12:30 AM 7/25/01 -0500, Gregg Vanderheiden wrote:
>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
>elses?
>
>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)
>
>G
>
>
>-- ------------------------------
>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/>
>FAX 608/262-8848
>For a list of our listserves send "lists" to listproc@trace.wisc.edu
><mailto:listproc@trace.wisc.edu>
>
>
>-----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
>To: WAI GL
>Subject: RE: guideline 7.1 about screen flickering (fwd)
>
>I don't think that this image is OK, unless the group feels that the
>"until
>user agents" part of the checkpoint means it is no onger applicable. It
>moves
>at something between 5 and 25 Hz in my viewer, and may preset problems
>with
>concentration or photosensitive epilepsy.
>
>I think that most browsers now allow people to stop the animation, but
I
>do
>not think I am in a position to decide that for the group. Could we
>please
>add it to the agenda as a matter of some urgency.
>
>Cheers
>
>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,
>France)
>
>---------- 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.
>They
>really need to change their wording to 'element flicker' or something.
>By
>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
>user
>agents allow users to control flickering, avoid causing the screen to
>flicker."  Here's the link to the checklist item:
>http://www.w3.org/TR/WCAG10/wai-pageauth.html#tech-avoid-flicker
>
>How can I determine if the gif in question is within the guidelines?
>(gif
>attached)  If it is not, I guess I can ask for a non-animated gif.
>
>Terrie
>
>---------------------------------------------
>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

Anne Pemberton
apembert@erols.com

http://www.erols.com/stevepem
http://www.geocities.com/apembert45
Received on Wednesday, 25 July 2001 09:16:33 GMT

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