Thread Subject: Fix to General and REd Flash definition

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From: Gregg Vanderheiden
Date: Tue, Sep 04 2007 2:45 PM

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

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