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Re: Another summary of alt="" issues and why the spec says what it says

From: Leif Halvard Silli <lhs@malform.no>
Date: Sat, 19 Apr 2008 18:09:26 +0200
Message-ID: <480A1936.2050402@malform.no>
To: Ian Hickson <ian@hixie.ch>
CC: Jim Jewett <jimjjewett@gmail.com>, david.dailey@sru.edu, John Foliot <foliot@wats.ca>, HTML4All <list@html4all.org>, Dan Connolly <connolly@w3.org>, HTML WG <public-html@w3.org>, "Michael(tm) Smith" <mike@w3.org>, wai-xtech@w3.org, Al Gilman <Alfred.S.Gilman@ieee.org>

Ian Hickson 08-04-18 02.47: 
> On Thu, 17 Apr 2008, Jim Jewett wrote:
> > > 
> > > ... sometimes there simply is no alternative text available. Examples 
> > > I can think of that have been mentioned so far include:
> > > 
> > >  * Images uploaded by a blind user before that user has had a chance 
> > > to ask his friends to describe the images to him.
> > 
> > Unlabeled Photo 3, taken on 2008-04-17.
>
> That would be a fine caption -- but as it should be visible to everyone, 
> not just those who can't see the image, it doesn't consist of good 
> alternative text (since if the alt attribute had this value, you'd be 
> saying stuff twice for the users who use alt text, which is worse than 
> saying it once).
>   
[ snipped losts of same thing examples ]

What you are saying here, Ian, is that it would be better user 
experience for a sighted, if this text was was used as a caption. And 
when you talk about "saying stuff twice", you calculates in, that it 
should have been used as captions.

But,

   1. To say that it should be in the caption, is an author advice.
      Authors are not obligued to staff images with captions and
      headers. In fact, there can be many times where the author prefers
      to not do that at all. After all, the sighted can see the image
      anyhow. And there might be other things in the page giving the
      sighted (enough) context.

   2. Speaking about how much work it is (2 days per week for a
      professional photographer, I think yhou said) adding alt text, it
      would not be less work adding the same text as caption. In fact,
      it could be more work adding a separate element thant it would be
      adding a text inside @ALT. What is simplest for the author,
      depends on the tool, the design of the page and so on and so
      forth. [And thus, the fact that Explorer has showed @ALT text as
      tool-tips can, as someone was mentioning, have had an effect on
      the use of alt.]

   3. This doesn't really help anyone, but it can just as well be the
      caption or the header that is a duplicate of the ALT text. As the
      opposite. This depends of what is written first.


In an off-list reply to me, you, Ian, again pointed to the below 
paragraph from WCAG 2 [1], as an example of a WCAG text requiring 
duplicate ALT text (you and Steve allready discussed this text a few 
times, so I think I do no harm mentioning that you took it up with me 
off-list  you have also expressed roughly the same thing in public a 
few times):

    "Sometimes content is primarily intended to create a specific
    sensory experience that words cannot fully capture. Examples include
    a symphony performance, works of visual art etc. For such content,
    text alternatives at least identify the non-text content with a
    descriptive label and where possible, some descriptive text. If the
    reason for including the content in the page is known and can be
    described it is helpful to include that information."

When you feared that the above WCAG 2 advice could lead to duplicate alt 
text, then - again - it must have been that you were calculating in 
that, whatever the alt text said, would also - or should instead - be 
said in a header or an caption.

However, I think there for the most part is agreement that the above 
WCAG 2 text speaks about a use case where adding an image caption or 
image header would harm the experience for the sighted user. Or - and 
this is the same thing - where the *author* did not want to disturb the 
pure image experience or the pure sound/video performance experience 
(quote: "a symphony performance") with a caption or a header.

The above advice for instance goes against offering a direct link to 
'great_painting.jpg', for those that want to experience a full page 
version of the the image. On should instead offer a real web page with 
an embedded 'great_painting.jpg' and an alt text for it.

Related but not the same thing - and hitherto unsolved in HTML 5: The 
above text also speaks about having replacement text for audio content. 
(Allthough, it would perhaps be possible to use <FIGURE> if one hid the 
caption or something.)

[1] 
http://www.w3.org/TR/2007/WD-UNDERSTANDING-WCAG20-20071211/text-equiv-all.html
-- 
leif halvard silli
Received on Saturday, 19 April 2008 16:10:15 UTC

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