- From: <bugzilla@jessica.w3.org>
- Date: Tue, 25 Sep 2012 22:01:23 +0000
- To: public-html-a11y@w3.org
https://www.w3.org/Bugs/Public/show_bug.cgi?id=19055
Summary: HTML5 Lacks a Way to Programmatically-Determine
Missing Text Alternatives
Product: HTML WG
Version: unspecified
Platform: PC
URL: http://dev.w3.org/html5/spec/text-level-semantics.html
#unknown-images
OS/Version: All
Status: NEW
Keywords: a11y, a11y_text-alt
Severity: enhancement
Priority: P3
Component: HTML5 spec
AssignedTo: dave.null@w3.org
ReportedBy: contributor@whatwg.org
QAContact: public-html-bugzilla@w3.org
CC: ian@hixie.ch, jan.richards@utoronto.ca, mjs@apple.com,
mike@w3.org, public-html-wg-issue-tracking@w3.org,
public-html@w3.org, contributor@whatwg.org,
w3c@kliehm.com, public-html-a11y@w3.org
This was was cloned from bug 9213 as part of operation LATER convergence.
Originally filed: 2010-03-08 16:39:00 +0000
Original reporter: Laura Carlson <laura.lee.carlson@gmail.com>
================================================================================
#0 Laura Carlson 2010-03-08 16:39:42 +0000
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SPEC SECTIONS:
Images whose contents are not known [1]
Guidance for conformance checkers [2]
BUG DESCRIPTION:
HTML5 Lacks a way to programmatically determine [3] where images whose contents
are not known to be detected and labeled as such. Consider creating a "missing"
attribute.
OUTCOMES OF FIXING THE BUG:
* A "missing" attribute would provide a practical method of detection,
handling, and future improvement.
* Possibilities for crowdsourcing exist with the addition of a "missing"
attribute It should be reasonably easy to maintain a hash of images with
@missing and the obtain value(s) submitted for them. We would need a canonical
URI (or in HTML5, an 'origin') for the document and an ID for the image, but if
we had a service (either local or remote) that accepted the URI and its @alt
value, then users of AT could associate the values as needed. The worst case is
that nothing is returned. (The second-worst case is that it's a bogus value,
but the owner of the document could manage submitted @alt content.) The pointer
to where to send this information could be in a <link> element, and it could be
a standard HTTP request, or a transaction using the HTML5 Database object. It
could be hosted locally, or by a third party. This idea would get around one of
the biggest problems with around images: that we can see something is wrong
with someone else's content, but can't do anything about it. With this method
people who know what they're doing could directly impact the accessibility of
another organization's content. It also helps image gallery sites since the
image creator or anyone who views the image could propose usable @alt with an
extremely low-bandwidth solution. If this method is used then we'd have to
specify @missing, and that any image with that attribute also needs an ID, or
they wouldn't be associable by the UA/AT. Then we'd need to specify the @rel
attribute for the <link> to the mechanism for associating the @alt.
* Would be valid and in accord with Accessibility Coordination Group's
"Consensus Resolutions on Text alternatives in HTML 5". [4]
ATTRIBUTE NAME:
If it is not too long, "notextalternative" could be a suitable name instead of
"missing" for this attribute. The image could be missing any one of text
alternatives in the set of valid options for conformance checkers.
REFERENCES:
http://dev.w3.org/html5/spec/text-level-semantics.html#unknown-images [1]
http://dev.w3.org/html5/spec/text-level-semantics.html#guidance-for-conformance-checkers
[2]
http://www.w3.org/TR/UNDERSTANDING-WCAG20/conformance.html#uc-programmatically-determined-head
[3]
http://www.w3.org/2009/06/Text-Alternatives-in-HTML5 [4]
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
================================================================================
#1 Maciej Stachowiak 2010-03-23 06:14:58 +0000
--------------------------------------------------------------------------------
As far as I can tell, the text here requires validators to report an error if
alt is absent and none of the conditions applies:
http://dev.w3.org/html5/spec/Overview.html#guidance-for-conformance-checkers
"A conformance checker must report the lack of an alt attribute as an error
unless one of the conditions listed below applies:..."
In particular, the set of conditions there seems just as checkable as the set
in the Change Proposal. Therefore I think this bug should be resolved as
WORKSFORME.
================================================================================
#2 Ian 'Hixie' Hickson 2010-04-02 00:08:35 +0000
--------------------------------------------------------------------------------
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are
satisfied with this response, please change the state of this bug to CLOSED. If
you have additional information and would like the editor to reconsider, please
reopen this bug. If you would like to escalate the issue to the full HTML
Working Group, please add the TrackerRequest keyword to this bug, and suggest
title and text for the tracker issue; or you may create a tracker issue
yourself, if you are able to do so. For more details, see this document:
http://dev.w3.org/html5/decision-policy/decision-policy.html
Status: Did Not Understand Request
Change Description: no spec change
Rationale: I don't understand. Could you restate the bug description? Are you
asking for a way to programmatically detect (e.g. from JS?) that an image is
missing alt text?
================================================================================
#3 Laura Carlson 2010-11-30 13:16:46 +0000
--------------------------------------------------------------------------------
*** Bug 11441 has been marked as a duplicate of this bug. ***
================================================================================
#4 Martin Kliehm 2010-12-07 16:25:29 +0000
--------------------------------------------------------------------------------
Although a @missing attribute is not part of the text alternatives package, the
bug-triage sub-team doesn't think this is an accessibility task force priority.
================================================================================
#5 Laura Carlson 2011-06-07 08:09:22 +0000
--------------------------------------------------------------------------------
A missing attribute would provide a practical method of detection, handling,
and repair of missing text alternatives, after a conscious decision has been
made by the author to deliberately publish images without text alternatives. It
would:
* Allow an image without alt text be honestly labeled for it is: missing,
incomplete, lacking substance.
* Affirm that the author did not (and does not intend to) provide a text
alternative.
* Provide a machine checkable mechanism to locate missing alt text/enable tools
to quickly discern where "missing" has been used.
* Afford a practical means to mitigate damages after all else has failed,
allowing for crowdsourcing or metadata repair. AT would be at liberty to apply
a crowdsourced definition, to scour image metadata or or both, since the AT
knows that the author didn't apply a text alternative, it can inform the user
as to the potential deficiency in the located text(s).
* Support ethical accountability by promoting the development of responsible
tools and by advocating an effective enabling environment.
Jan Richards explained how this could work [1]:
1. the author drag-and-drops an image into an authoring tool (bypassing the
usual insert dialog)
2. the authoring tool has implemented a "live" accessibility checker (not
required by ATAG but a nice feature), so the image is immediately given a blue
squiggly underline (similar to red underlining of spelling errors) to indicate
no @alt value has been set.
3. BUT the author ignores the underlining, saves and close the document.
4. BUT the authoring tool has an accessibility option set to use the "missing"
mechanism to validate, so when the author has failed to address the
accessibility issue and the content is being closed, the tool adds @alt=" "
and the "missing" mechanism. (Ordinarily adding " " to the @alt would be
considered a repair of the alternative text, but the missing mechanism tells
user agents to ignore it...so ATAG2 B.2.4.3 is met).
It is possible to require a set of programmatically valid options which
maintains the integrity of the markup and aids accessibility while addressing
business needs.
--
[1] http://lists.w3.org/Archives/Public/public-html/2009Aug/1009.html
================================================================================
#6 Ian 'Hixie' Hickson 2011-06-13 23:43:33 +0000
--------------------------------------------------------------------------------
Before it would be reasonable to deploy something like this in HTML proper, we
should first determine whether this is something that authors are likely to
actually use.
I would recommend defining a class name, e.g. "alt-missing-intentionally", that
could be handled in the way described above, and then encouraging people who
need this feature to use that for now. If it takes off, then it would make
sense to anoint it in the spec.
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are
satisfied with this response, please change the state of this bug to CLOSED. If
you have additional information and would like the editor to reconsider, please
reopen this bug. If you would like to escalate the issue to the full HTML
Working Group, please add the TrackerRequest keyword to this bug, and suggest
title and text for the tracker issue; or you may create a tracker issue
yourself, if you are able to do so. For more details, see this document:
http://dev.w3.org/html5/decision-policy/decision-policy.html
Status: Partially Accepted
Change Description: none yet
Rationale: I have marked this LATER so that we can look at this again once
people have had a chance to demonstrate the authoring demand for this feature.
================================================================================
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Received on Tuesday, 25 September 2012 22:01:37 UTC