Thread Subject: Fix to General and REd Flash definition
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From: Gregg Vanderheiden
Date: Tue, Sep 04 2007 2:45 PM
Subject: Fix to General and REd Flash definition
Jared Smith pointed out an oversight in our definition of Flash Thresholds.
We need to add "when viewed at normal viewing distance" to the end of item
3 as shown below.
I am forwarding this amendment both to WCAG and TEITAC with a recommendation
to make the change.
general flash and red flash thresholds
a sequence of flashes or rapidly changing image sequences where all three of
the following occur:
1. there are more than three flashes within any one-second period; and
2. the flashing is below 50 Hz; and
3. the combined area of flashes occurring concurrently and contiguously
occupies more than a total of .006 steradians (25% of any 10 degree visual
field on the screen) when viewed at normal viewing distance.
Gregg
------------------------
Gregg C Vanderheiden Ph.D.
Professor - Depts of Ind. Engr. & BioMed Engr.
Director - Trace R & D Center
University of Wisconsin-Madison
< <http://trace.wisc.edu/> http://trace.wisc.edu/> FAX 608/262-8848
DSS Player at http://tinyurl.com/dho6b
If Attachement is a mail.dat try <http://www.kopf.com.br/winmail/>
http://www.kopf.com.br/winmail/
<http://trace.wisc.edu:8080/mailman/listinfo/>
From: Loretta Guarino Reid
Date: Tue, Sep 04 2007 3:05 PM
Subject: Re: Fix to General and REd Flash definition
I'll put this into this week's survey.
Loretta
On 9/4/07, Gregg Vanderheiden < = EMAIL ADDRESS REMOVED = > wrote:
>
>
>
>
> Jared Smith pointed out an oversight in our definition of Flash Thresholds.
>
>
>
> We need to add "when viewed at normal viewing distance" to the end of item
> 3 as shown below.
>
>
>
> I am forwarding this amendment both to WCAG and TEITAC with a recommendation
> to make the change.
>
>
>
>
> general flash and red flash thresholds
>
> a sequence of flashes or rapidly changing image sequences where all three of
> the following occur:
>
> 1. there are more than three flashes within any one-second period; and
>
> 2. the flashing is below 50 Hz; and
>
> 3. the combined area of flashes occurring concurrently and contiguously
> occupies more than a total of .006 steradians (25% of any 10 degree visual
> field on the screen) when viewed at normal viewing distance.
>
>
>
>
>
> Gregg
>
> ------------------------
>
> Gregg C Vanderheiden Ph.D.
> Professor - Depts of Ind. Engr. & BioMed Engr.
> Director - Trace R & D Center
> University of Wisconsin-Madison
> <http://trace.wisc.edu/> FAX 608/262-8848
>
> DSS Player at http://tinyurl.com/dho6b
>
> If Attachement is a mail.dat try http://www.kopf.com.br/winmail/
>
>
>
>
>
>
>
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