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[Bug 10455] New: Mint a describedby attribute for the img element

From: <bugzilla@jessica.w3.org>
Date: Thu, 26 Aug 2010 12:28:16 +0000
To: public-html-a11y@w3.org
Message-ID: <bug-10455-3290@http.www.w3.org/Bugs/Public/>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=10455

           Summary: Mint a describedby attribute for the img element
           Product: HTML WG
           Version: unspecified
          Platform: All
               URL: http://dev.w3.org/html5/spec/embedded-content-1.html#t
                    he-img-element
        OS/Version: All
            Status: NEW
          Keywords: a11y, a11y_text-alt
          Severity: normal
          Priority: P2
         Component: HTML5 spec (editor: Ian Hickson)
        AssignedTo: ian@hixie.ch
        ReportedBy: laura.lee.carlson@gmail.com
         QAContact: public-html-bugzilla@w3.org
                CC: mike@w3.org, public-html@w3.org,
                    public-html-a11y@w3.org


HTML5 fails to adequately provide the functions that had been provided through
the longdesc HTML 4 attribute. Those functions are:

1. A direct, reusable programmatically associated mechanism to a long
description of an image without a forced visual encumbrance or default visual
indicator.
2. A method to reference a longer description of an image, without including
the content in the main flow of a page. 

Many images cannot be sufficiently described with other long description
techniques. For instance, longdesc currently provides a solution for describing
the content of images to the blind when it would be:

* Visually apparent and redundant to a sighted person.
* Unacceptable to the marketing department due to aesthetic considerations.
Artists, designers and marketers do not want their visual designs
changed/ruined; whether that's with visible link text or a disclosure widget.

There is currently absolutely no direct way of doing that.

PURPOSE

The purpose of describedby would be to describe an image to people who can not
see. It is an accommodation for the blind and visually impaired.

It's aim is to provide what the visual provides. Like the HTML4 longdesc
attribute a correct and proper describedby is redundant for people who have
sight. 

USE CASES

* Data Visualization i.e. charts and graphs
* Diagrams
* Cartoons, drawings, illustrations,  etc

REQUIREMENTS

1. A programmatic mechanism to reference a specific a structured description,
internal or external to the document.
2. A way to inform users and authors that a description is present/available
via user agent (UAs could provide an option to reveal the content of
describedby via a context menu, preference, or switch etc.). This also affords
a practical method for the curious and for developers who want a tool to check
the describedby descriptive content and keep it up to date.
3. A device independent way to access the descriptive content.
4. An explicit provision that accessing descriptive content, whether internal
or external to the document containing the image, does NOT take the user away
from the user's position in the document containing the image where the verbose
descriptor was invoked.
5. A way to provide user control over exposition of the descriptor so that
rendering of the image and its description is not an either/or proposition. A
visual indicator of the description should NOT be a forced visual encumbrance
on sighted users by default.
6. A method to reference a longer description of an image, without including
the content in the main flow of a page. 

REFERENCES:

Examples of longdesc in the Wild with No Visual Link Text Clutter 
http://www.w3.org/html/wg/wiki/LongdescRetention#Examples_with_No_Visual_Link_Text_Clutter

longdesc in HTML 4.01
http://www.w3.org/TR/REC-html40/struct/objects.html#adef-longdesc-IMG

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Received on Thursday, 26 August 2010 12:28:17 UTC

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