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Re: Where does flicker come from?

From: Jon Gunderson <jongund@staff.uiuc.edu>
Date: Mon, 24 May 1999 17:03:19 -0500
Message-Id: <199905242203.RAA29773@staff2.cso.uiuc.edu>
To: Wendy A Chisholm <chisholm@trace.wisc.edu>, Ian Jacobs <ij@w3.org>, w3c-wai-gl@w3.org
Cc: w3c-wai-ua@w3.org
I think we already have these in the guidelines.  So I think we are covered
for flicker issues.  But I will check to make sure.

At 04:22 PM 5/24/99 -0500, Wendy A Chisholm wrote:
>Flicker and other visual events that may cause a seizure (such as quick
>changes from light to dark) may be created by the following 4 ways (there
>may be more):
>1.  scripting
>2.  animated images
>3.  applets
>4.  embedded multimedia objects
>possible suggestions for UA:
>1.  allow users to disable scripting, applets, and multimedia objects 
>2.  allow the user to control the rate of change (of scripts, applets, and
>multimedia objects).
>3.  allows users to pause animated images (i.e. only show first or last
>frame, or step through frames at user request)
>At 01:49 PM 5/24/99 , Ian Jacobs wrote:
>>We say in checkpoint 7.1 of the Web Content Accessibility Guidelines
>> Until user agents allow users to control flickering, 
>> avoid causing the screen to flicker.
>>I'd like to tell the UA WG how flicker may be caused so
>>that UAs can prevent it. Can someone explain what markup
>>or settings lead to flicker?
>>Thank you,
>> - Ian
>>[1] http://www.w3.org/TR/WAI-WEBCONTENT/#gl-movement
>>Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
>>Telephone May 1999 only:     (212) 688-4489
>>Cell phone May 1999:         (917) 450-8783
>>Otherwise Tel/Fax:           (212) 684-1814
Jon Gunderson, Ph.D., ATP
Coordinator of Assistive Communication and Information Technology
Division of Rehabilitation - Education Services
University of Illinois at Urbana/Champaign
1207 S. Oak Street
Champaign, IL 61820

Voice: 217-244-5870
Fax: 217-333-0248
E-mail: jongund@uiuc.edu
WWW:	http://www.staff.uiuc.edu/~jongund
Received on Monday, 24 May 1999 18:04:39 UTC

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