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Re: GIFs

From: David Poehlman <poehlman1@comcast.net>
Date: Fri, 28 Mar 2003 15:46:30 -0500
To: "Roberts, Elizabeth A." <ROBERTS@hfsecmail.rdh.ohio-state.edu>, w3c-wai-ig@w3.org
Message-id: <00eb01c2f56b$1dd2b850$6501a8c0@handsontech>

in my tests of flicker rates, it is dependant on the system you use.  It is
quite possible that a flicker rate that is fast enough to over come the
boundary on one machine will be slow enough not to on a slower machine.
The idea of possibly looking at whether or not something will flicker is
good but to "fix it" may not be.  Also, this is fixable in some user agents
depending on how it is implemented.  I had not gotten into this discussion
before now till it dawned on me that I don't notice flickering in pages even
if they are supposed to flicker because my rendering engine prevents it.  I
use accessible testing tools to check for this anyway.

----- Original Message -----
From: "Roberts, Elizabeth A." <ROBERTS@hfsecmail.rdh.ohio-state.edu>
To: <w3c-wai-ig@w3.org>
Sent: Friday, March 28, 2003 3:32 PM
Subject: Re: GIFs

Vincent Flanders wrote:
> I haven't examined every accessibility verification tool out there, but
> it seems rather strange to me the ones I've looked at want me to
> manually examine each GIF file for flicker. Even *I* know that it's
> possible for a programmer to examine the contents of a GIF file and tell
> if it's animated. Are there any accessibility tools out there that check
> the GIFs for you and eliminate the ones that obviously aren't animated?

This is slightly different, but closely related: Deque
<http://www.deque.com/> creates a product called RAMP that detects
unacceptable flicker rates and fixes them.

From <http://www.deque.com/products/rampsection508.htm>:

"Section 508 Paragraph (j) Pages shall be designed to avoid causing the
screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.

"Automatically detects flickering rates with unacceptable frequency
Auto Remediation of animated gifs, marquee elements, and other blinking

I just happened to go to a product demonstration recently, but haven't had a
chance to test it out for myself; they did use the product to change a gif
during the demonstration and it seemed to work well.

--Liz Roberts
Received on Friday, 28 March 2003 15:53:16 UTC

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