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re-rewrite Action-504 2.9.1 Background Image Toggle

From: Jim Allan <jimallan@tsbvi.edu>
Date: Thu, 10 Mar 2011 10:12:41 -0600
Message-ID: <AANLkTinX4SB61yZL69eoR8sJRuERf8XhGrCBcuqCYWZ7@mail.gmail.com>
To: WAI-ua <w3c-wai-ua@w3.org>
based on meeting on 10 March 2011
a. added 'recognized' to sc
b. moved info about 'background images with alternative content' from
Resources a Note: in the intent
c. removed para in the intent about changing bg image to solid color image

2.9.1 Background Image Toggle: The user can have all
recognized 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.

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)

Note: 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.)

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 to hot 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. 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 Thursday, 10 March 2011 16:13:16 GMT

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