- From: Christophe Strobbe <christophe.strobbe@esat.kuleuven.be>
- Date: Mon, 17 Sep 2007 10:44:55 +0200
- To: w3c-wai-gl@w3.org
Hi Gregg, At 07:00 17/09/2007, you wrote: >Blink and flash have now been redefined. Does this address the concern? > > > >blink > > > >switch back and forth between two visual states in a way that that >does not qualify as ><http://www.w3.org/WAI/GL/WCAG20/#flash-def>flash (e.g. it is too >slow or the change in relative luminance is too small to qualify as flashing) > >Note: The slower blink is in contrast with ><http://www.w3.org/WAI/GL/WCAG20/#flash-def>flashing, which refers >to rapid changes in brightness which can cause seizures. See ><http://www.w3.org/WAI/GL/WCAG20/#general-thresholddef>general flash >and red flash thresholds. Yes, thanks, that addresses my concern. Best regards, Christophe > > > >flash > > > >a pair of opposing changes in relative luminance of 10% or more >where the relative luminance of the darker image is below 0.80 > >Note: Flash is characterized by rapid changes of relative luminance >occurring more than three times per second, while ><http://www.w3.org/WAI/GL/WCAG20/#blinksdef>blink is less than three >times per second. > >Note: See ><http://www.w3.org/WAI/GL/WCAG20/#general-thresholddef>general flash >threshold and red flash threshold for more precise information about >the applicability and constraints of flash. > > >Gregg > -- ------------------------------ >Gregg C Vanderheiden Ph.D. > > > > > -----Original Message----- > > From: w3c-wai-gl-request@w3.org > > [mailto:w3c-wai-gl-request@w3.org] On Behalf Of Christophe Strobbe > > Sent: Wednesday, September 12, 2007 4:57 AM > > To: wcag > > Subject: SC 2.2.2 (Blinking) and contrast ratio > > > > > > Hi, > > > > The following question came out of some work on the Unified > > Web Evaluation Methodology (UWEM) [1]. > > The May 2007 draft of WCAG 2.0 defines blink as "turn on and > > off between 0.5 and 3 times per second", with a note saying: > > "The slower blink is in contrast with flashing, which refers > > to rapid changes in brightness which can cause seizures. See > > general flash and red flash thresholds." > > > > However, the definition of blink does not specify a contrast > > ratio between the on and of states, so any blinking fails the > > success criterion, even if the contrast between the two > > states is very low. > > Of course, low contrast would fail SC 1.4.3 (Contrast > > (Minimum)), but evaluators, especially automated tools, would > > want to establish whether blinking content fails SC 2.2.2 by > > itself, regardless whether it passes or fails SC 1.4.3. > > So, my question is: does *all* blinking content fail SC > > 2.2.2? (I assume it currently does.) Should we add a note > > about this to the definition of blink? > > > > Best regards, > > > > Christophe > > > > [1] <http://www.wabcluster.org/uwem1_1/> UWEM is based on > > WCAG 1.0; checkpoint 7.2 covers blinking content. -- Christophe Strobbe K.U.Leuven - Dept. of Electrical Engineering - SCD Research Group on Document Architectures Kasteelpark Arenberg 10 bus 2442 B-3001 Leuven-Heverlee BELGIUM tel: +32 16 32 85 51 http://www.docarch.be/ Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
Received on Monday, 17 September 2007 08:45:17 UTC