Hello all,
I have a second suggestion for the alt problem that will require the use of WAI-ARIA,
namely aria-describedby. Drawback: That is currently only valid in HTML 5. But it would be
the better solution since alternative text and caption text are two different things (see
also
http://en.wikipedia.org/wiki/Wikipedia:Alternative_text_for_images).
Using WAI-ARIA the solution would be:
1. If [[File:...|alt=...|...]] is given, use this text for the alt attribute.
2. If no alt text exists, use the “simplified” file name.
3. Add aria-describedby="ImageCaption" to the img tag. (With ImageCaption being
the id of the caption.)
The screen reader then can associate the caption with the image.
Cheers,
Maria
P.S. Please not that the handling of alt text currently differs depending on whether you
use thumb, frameless or pixel (see
http://de.wikipedia.org/wiki/Benutzer:Raymond/alt). It
must be consistent.