[whatwg] Alt text authoring Re: Conformance for Mail clients

Sun Apr 22 16:31:46 PDT 2007

>
> When screen readers find img without alt, there typically attempt to
>
fake alternative text using the src attribute. This can be done crudely
> (just reading the whole path) or selectively (just reading the filename,
> e.g. gallery2.jpg). Since authors will continue to fail to provide
> alternative text, screen readers are likely to continue employing such
> heuristics, defeating any attempt to attach a special new meaning to
> missing alt attributes. If images without alt are to be allowed, then
> noalt would be a reasonable hint.
>
> --
> Benjamin Hawkes-Lewis

When UAs do what you describe, do they provide a way to download the image
(text browsers) or indicate that what's missing in an image (screen
readers)?  What UAs?  Is this different from how they currently behave when
alt is present but blank?

This page:
<!DOCTYPE html>
<title>IMG test</title>
<ol>
<li>Image represents a <img src=PICT0023.JPG alt=tree>
<li>Image is content <img src=PICT0023.JPG>
<li>Image is decorative <img src=PICT0023.JPG alt=''>
</ol>

Is rendered by Lynx (on my machine) as:
    1. Image represents a tree
    2. Image represents is content [PICT0023.JPG]
    3. Image represents is decorative

Only in (2) does Lynx indicate that the image is missing.  That's the
behavior I would expect (even with noalt)

Neither Firefox nor Konqueror distinguish between (2) and (3) with images
disabled.

"noalt" is a good idea and leaves no ambiguity.

The current draft does say that a missing alt should be treated as if it's
blank.  Should that stay the same, or should special semantics be defined
for a missing alt?  Would any new semantics affect the DOM alt attribute?
(I don't think it should.)  I'd still like to know what other current UAs
(screen readers) do with a missing alt.

-- 
Jon Barnett
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