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Re: Animated Gifs and Screen readers

From: Patrick H. Lauke <redux@splintered.co.uk>
Date: Mon, 30 Aug 2004 18:53:16 +0100
Message-ID: <4133698C.6030202@splintered.co.uk>
To: 'WAI-IG' <w3c-wai-ig@w3.org>

Michael R. Burks wrote:
 > Does anyone know of any issues with animated gifs or other animated 
 > and screen readers?

In and of itself, an animated gif is no different from any other image. 
A screen reader (in conjunction with the browser) will treat it like it 
does all images.
In general:
- if it has an ALT attribute, it will read that out;
- if it's a decorative image with a null ALT, it should silently pass it 
- if there's no ALT set, it should announce it as "image", usually 
followed by the file name.

(this is not a comprehensive list of behaviours, as it may change 
depending on the exact screen reader used and/or things like verbosity 
settings chosen by the user...but it should give you an indication)

So, technically, it's not a problem. Now, there are other things you 
need to take into consideration when using animated gifs. If there's 
information in the different frames of the animation (e.g. text changing 
from one frame to the next), you need to ensure that said information is 
available in alternative format (e.g. text of all different frames in 
full in the image's ALT).
Also make sure that the rate at which the image changes doesn't cause 
flicker that could pose a problem to users with photosensitive epilepsy. 
  (see WCAG 1.0 guideline 7 http://www.w3.org/TR/WCAG10/#gl-movement )

Patrick H. Lauke
re·dux (adj.): brought back; returned. used postpositively
[latin : re-, re- + dux, leader; see duke.]
www.splintered.co.uk | www.photographia.co.uk
Received on Monday, 30 August 2004 17:52:48 UTC

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