RE: alt and authoring practices

Anne wrote:

> With nobody having data of usage on the Web the position of the editor
> seems more reasonable to me.

Couldn't our Google-employed editor could offer some data?

It seems like gathering data from various sources would
advance this debate more usefully than any amount of
speculation on what might be.

Matt
--
Matt Bonner
Hewlett-Packard Company

-----Original Message-----
From: public-html-request@w3.org [mailto:public-html-request@w3.org] On
Behalf Of Anne van Kesteren
Sent: Wednesday, April 16, 2008 4:09 AM
To: Steven Faulkner; James Graham
Cc: public-html@w3.org; wai-xtech@w3.org; wai-liaison@w3.org
Subject: alt and authoring practices


On Wed, 16 Apr 2008 12:32:59 +0200, Steven Faulkner
<faulkner.steve@gmail.com> wrote:
> Take the example of the john's flickr page cited by Ian earlier, that
> page contained 24 images without an alt attribute. There is no
> reliable means to determine whether any of these images contain
> information important enough "critical to understanding the page" to
> convey their presence to the user. If all our conveyed in some way,
> the user would hear the word "graphic" (for example) 24 times
> sprinkled throughout the text content of the page, adding to the
> cognitive load on the user without aiding understanding. To get any
> information from these images, the user would have to set "virtual"
> focus to each one in turn (for example in JAWS, users can navigate
> from image to image using the G key) and then use a series of
> keystrokes to query the attribute values (src for example).  In most
> cases the attributes will not contain any useful information, so would
> be an exercise in futiltity for the user. As well as taking a very
> long time.
>
> does that help?

What do you base the assumption on that when pages omit the alt attribute
they likely mean setting it to the empty string where as they have the alt
attribute it likely is correct? If you want to consider non-conforming
pages in this debate and it seems you do you really have to consider the
likelyhood of all the mistakes that could be made.

For alternate text we have three types of images: Images for which there's
alternative text (available). Images for which there's no alternative text
(missing). Images for which the alternative text is the empty string
(empty).

Current authoring practices have these three variants: <img alt="...">,
<img alt="">, and <img>.

Given that authors make mistakes there are nine possibilities of authoring
images:

  1. <img alt="..."> - available -> Correct usage
  2. <img alt=""> - available -> Incorrect usage
  3. <img> - available -> Incorrect usage
  4. <img alt="..."> - missing -> Incorrect usage
  5. <img alt=""> - missing -> Incorrect usage
  6. <img> - missing -> Correct usage
  7. <img alt="..."> - empty -> Incorrect usage
  8. <img alt=""> - empty -> Correct usage
  9. <img> - empty -> Incorrect usage

It seems your assumption is that on average 9 is more common than 3 and 6
combined and that therefore <img> should be equivalent to <img alt=""> as
far as user agents go and we should have an alternative solution to cater
for 6.

It seems the assumption from the editor is that on average all incorrect
usage is about as likely and that therefore 3 and 6 should win from 9 and
that therefore <img> might as well be used for this case.

With nobody having data of usage on the Web the position of the editor
seems more reasonable to me.


--
Anne van Kesteren
<http://annevankesteren.nl/>
<http://www.opera.com/>