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Action-504 rewrite 2.9.1 Background Image Toggle

From: Jim Allan <jimallan@tsbvi.edu>
Date: Mon, 14 Feb 2011 15:43:46 -0600
Message-ID: <AANLkTinxnDnoYu14SZKbH+BhcxXWGcv5iQLn3YNkuz=r@mail.gmail.com>
To: WAI-ua <w3c-wai-ua@w3.org>
2.9.1 (former 4.9.1) Background Image Toggle: The user can have all
background images shown or hidden. (Level A)

Intent:

It can be difficult for some people to read text or identify images
when the background is complex or doesn't contrast well with the
foreground. Allowing users to disable the display of background images
helps ensure that foreground content remains easy to read. This can
also help remove purely decorative distractions, which is important
for some users.

Users could have the option to have non-transparent backgrounds of a
solid color of their choice drawn behind text, rather than turning off
background images.

Because background images occasionally convey important information,
when their display is turned off the user agent should give users
access to any alternative content associated with them.

This checkpoint does not address issues of multi-layered renderings
and does not require the user agent to change background rendering for
multi-layer renderings (refer, for example, to the z-index property in
Cascading Style Sheets, level 2 ([CSS2], section 9.9.1)

Examples:

James has a reading disability where he needs text to be clear from
distractions that are not related to the text. He configures his user
agent not to load background images and navigates to a web page. James
then gets only the text from the web page without any images
interfering with what he is reading.

Related Resources:

1. In CSS, background images may be turned on/off with the background
and background-image properties ([CSS2], section 14.2.1).

2. The z-index property in Cascading Style Sheets, level 2 ([CSS2],
section 9.9.1)

3. Because background images occasionally convey important
information, when their display is turned off the user agent should
give users access to any alternative content associated with them. (At
the time of this writing, HTML does not support alternative content
for background images, but this may be supported in other technologies
or future versions.)

4. See Success Criteria 1.4.1 "Configure Text" for more information
related to background colors.

-- 
Jim Allan, Accessibility Coordinator & Webmaster

Texas School for the Blind and Visually Impaired

1100 W. 45th St., Austin, Texas 78756

voice 512.206.9315    fax: 512.206.9264  http://www.tsbvi.edu/

"We shape our tools and thereafter our tools shape us." McLuhan, 1964
Received on Monday, 14 February 2011 21:44:18 GMT

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