Thread Subject: Re: Photo-Seizure Language

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From: Thomas Albin
Date: Mon, Jul 02 2007 10:45 AM

Thank you, Gregg.

On Jul 2, 2007, at 11:07 AM, Gregg Vanderheiden wrote:

> Hi Tom
>
>
>
> You are correct on both counts.
>
>
>
> Both of those ARE TAKEN INTO ACCOUNT in the âgeneral flash and red
> flash thresholdsâ FOR SOFTWARE
>
>
> But NEITHER is covered in the current HARDWARE provisions - and
> they need to be.
>
>
> Good catch.
>
>
>
> Will fix.
>
>
>
> PS (one good place to find the need for this would be flashers for
> phones in noisy areas or for people who are deaf. They need to be
> bright but should not flash more than 3 times a second and 2hz or
> slower is better.)
>
>
> Gregg
> -- ------------------------------
> Gregg C Vanderheiden Ph.D.
>
>
>
>
>
> From: = EMAIL ADDRESS REMOVED = [mailto:teitac-general-
> = EMAIL ADDRESS REMOVED = ] On Behalf Of Thomas Albin
> Sent: Monday, July 02, 2007 9:04 AM
> To: TEITAC General Interface Accessibility Subcommittee
> Subject: Re: [teitac-general] Photo-Seizure Language
>
> Hi All,
>
> Didn't we originally set a proscribed range for the flash
> frequency, e.g. greater than 3 Hz and less than or equal to 55 Hz?
> The literature on Photosensitive Seizures (PSS) seems very
> consistent that that both the very low frequencies and the higher
> frequencies are of less concern in regard to PSS.
>
>
>
> Also, wasn't the 20 candela/meter squared (20 cd/m2) limit a
> description of a difference, rather than an absoloute? For
> example, Binnie et al in the SMPTE paper describing the PSS limits
> set for viewing television images set a 20 cd/m2 intensity limit,
> but on a change relative to maximum screen luminance, where the
> maximum screen luminance is 100 cd/m2. Perhaps we should consider
> a relative intensity limit of 20% relative to maximum screen
> luminance?
>
>
>
> Best regards,
>
> Tom
>
> On Jul 1, 2007, at 11:26 PM, Gregg Vanderheiden wrote:
>
>
>
>
> We are supposed to come up with language for general coverage of
> seizure disorders.
>
> We have agreed to follow the Web language (except tweaked to fit
> 508 - e.g. imperative voice and use of âmustâ)
>
> For hardware we talked of restricting this to only severe problems
> so that LEDs etc are clearly NOT covered.
>
> The approach below eliminates all small flashing objects unless
> they are VERY bright (like a flash tube) â or very large ( so it
> would be comparable to the software provision).
>
> If this looks OK we can go with this as a placeholder for our next
> draft and work to figure out the proper YYY value and language.
>
> ---------------
>
> Photo-Seizure
>
> Product software must not flash more than 3 times in any one second
> period unless the flash is under the general flash and red flash
> threshold.
>
> Product hardware must not flash more than 3 times in any one second
> period if the flash either:
>
> is greater than YYY candelas; or
> is greater than 20 candelas/sq meter and contiguously occupies more
> than a total of .006 steradians (25% of any 10 degree visual field).
>
> 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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