- From: Phill Jenkins <pjenkins@us.ibm.com>
- Date: Tue, 27 Oct 2009 22:42:10 -0500
- To: w3c-wai-ig@w3.org
- Cc: public-comments-wcag20@w3.org
- Message-ID: <OFFFC7AFE6.86A4D01A-ON8625765D.000EB704-8625765D.0014575E@us.ibm.com>
Is the duration of the flashing or flickering (i.e., more than one second of time) a factor in determining accessibility compliance to WCAG 2.0 See Success Criteria 2.3.1 http://www.w3.org/TR/WCAG20/#seizure "... do not contain anything that flashes more than three times in any one second period..." In my special case example, there is a slightly less than 1 second duration of 3 flashes in an Adobe Flash image at the top of a draft Shanghai EXPO 2010 page. WARNING - currently it flashes 3 times for slightly less than one second, then repeats several seconds later. see http://fr.expo2010.cn/indextest.htm Assuming the developer adds a capability to stop the repeating Adobe Flash movie, is it still a problem because it flashes 3 times, regardless of the duration (e.g., 1 second, 10 seconds, etc.)? Or does it need to flash more that 3 times a second of time for more that 1 second of duration? The "Understanding Guidelines 2.3" further mentions: "likely to cause seizure when viewed even for a second or two." see http://www.w3.org/TR/UNDERSTANDING-WCAG20/seizure.html metrics to consider: Frequency, Duration, and Size (the text only really address frequency and size, not duration) frequency: (or interval) more than 3 flashes per second of time? (3 to 50 Hz) duration: more than one second duration of time? if it flashes more than 3, but for less than 1 second, is it a problem? size: 341 x 256 pixel block or larger - see http://www.w3.org/TR/WCAG20/#general-thresholddef Since my example only flashes 3 times and not more than 3, and it soon may change to not repeat - Guidelines 2.3 says "more than three", then I think I do not have a problem, but I'm not sure - hence the question to the list. Your informed opinions welcomed. I also believe the text and explanation can be simplified. For example: 1. by addressing the three different metrics; frequency, duration, and size. 2. by addressing the lower and upper limits of each. For example, if the frequency is 40 times in a second, but only lasts 1 second or less, regardless of size it may be hardly noticeable and not be a problem. 3. add some more common passing and failing examples. The two existing ones are good. Regards, Phill Jenkins,
Received on Wednesday, 28 October 2009 03:42:46 UTC