[Bug 9212] New: Change the Generator Mechanism for img from Document Level to Element Level

http://www.w3.org/Bugs/Public/show_bug.cgi?id=9212

           Summary: Change the Generator Mechanism for img from Document
                    Level to Element Level
           Product: HTML WG
           Version: unspecified
          Platform: PC
               URL: http://dev.w3.org/html5/spec/text-level-
                    semantics.html#guidance-for-conformance-checkers
        OS/Version: All
            Status: NEW
          Keywords: a11y, a11y_text-alt
          Severity: normal
          Priority: P2
         Component: HTML5 spec bugs
        AssignedTo: dave.null@w3.org
        ReportedBy: laura.lee.carlson@gmail.com
         QAContact: public-html-bugzilla@w3.org
                CC: ian@hixie.ch, mike@w3.org, public-html@w3.org, public-
                    html-a11y@w3.org
        Depends on: 8171


SPEC SECTION: Image Guidance for conformance checkers [1] 

The generated mechanism should only be included at the element level with a
detection method like a "generated" attribute, rather than the document level.

If the generated option is left at document level, as in the current editor's
draft, it would be too easy for authors just to tag the document "generated"
and then forget to provide any text alternatives for images.


GENERATED EXAMPLE:

1. Author logs into the photo sharing site
2. Author uses the uploader feature to upload 50 pics of a vacation
(XYZ0001.png, XYZ0002.png,..., XYZ0050.png) into an album the author calls
"Paris 2009".
3. A prompt appears asking the author to write descriptive labels for each
image to facilitate text searching and access by people with disabilities.
4. The author logs off without adding individual text alternatives.
5. The photo sharing site assigns the @alt strings "Photo 1 of 50 of album
Paris 2009"
6. The author logs back in they still see "generated" indicators on the images
and/or the album that reminds them that the images are still lacking
descriptive labels.
7. The page will be HTML5_valid because it includes @alt
8. The feature will meet the proposed ATAG2 requirement because the "After
authoring session ended" repair used contextual information not available to
the user agent.
9. The page will NOT meet WCAG 2.0 because the text alternative does not serve
the equivalent purpose. 

Source: ATAG2 B.2.4 Assist authors to manage, edit, and reuse equivalent
alternatives for non-text objects - Jan Richards. [2] 


OUTCOMES OF FIXING THE BUG:

Outcomes of creating a "generator" attribute include:

* Enables tools to programmatically determine [3] where text alternatives are
needed and allow for future improvement. It would provide a practical method of
detection and handling. 

* Identifies/stamps any metadata repair as indeed a metadata repair. This makes
it clear it is a machine-generated patch-job and not a human-generated text
alternative. The two aren't the same and shouldn't be confused or on purpose or
otherwise. 

* Is harmony with proposed Authoring Tool Accessibility Guideline (ATAG) 2.0
B.2.4. [4]

* Is in accord with Accessibility Coordination Group's "Consensus Resolutions
on Text alternatives in HTML 5". [5]. 


REFERENCES:

http://dev.w3.org/html5/spec/text-level-semantics.html#guidance-for-conformance-checkers
[1]
http://lists.w3.org/Archives/Public/w3c-wai-au/2009AprJun/0016.html [2]
http://www.w3.org/TR/UNDERSTANDING-WCAG20/conformance.html#uc-programmatically-determined-head
[3]
http://www.w3.org/TR/ATAG20/#gl-manage-alts [4]
http://www.w3.org/2009/06/Text-Alternatives-in-HTML5 [5] 


HTML5 ISSUE AND CHANGE PROPOSAL:

This is associated with HTML TRACKER ISSUE-31 
http://www.w3.org/html/wg/tracker/issues/31

Change Proposal: Replace img Guidance for Conformance Checkers:
http://www.w3.org/html/wg/wiki/ChangeProposals/ImgElement20090126


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Received on Monday, 8 March 2010 16:36:37 UTC