[whatwg] <img> element comments

Dave Singer singer at apple.com
Wed Aug 15 10:42:28 PDT 2007

At 10:48  +0000 15/08/07, Ian Hickson wrote:
>  > > > * I would also suggest to put "If the src attribute is omitted,
>>  > > there is no alternative image representation." after the last
>>  > > statement on the alt attribute.
>>  >
>>  > Done. (I think. I edited a bunch of stuff before reading your comment
>>  > so it may be not quite what you meant.)
>>  And, as I mentioned in IRC, I think it should be defined that the value
>>  should resolve to a valid URI for an image, so that <img src="" alt="">
>>  isn't conforming, except in this rare case:
>>  <p xml:base="foo.png"><img src="" alt=""/></p>
>Ok but... what's an image? Do we exclude PDFs and SVG? (Safari and Opera
>respectively support those.)
>If we allow SVG, it's trivial to send XHTML as image/svg+xml and the
>processing is as defined then for HTML as for SVG, so why exlude HTML?
>If we disallow SVG, what's the definition? image/* that corresponds to a
>non-interactive bitmapped resource? What about WMFs? Why would those be
>As Simon asked on IRC, who are we helping by limiting what's allowed?

Making life a little easier for the browser implementers in what they 
might reasonably expect to find there?

Clearly images have to have a visual representation.  Embedding only 
audio, or ancillary data, here would be too weird.

Perhaps images are things that are non-temporal and with visual 
representation, or "slightly temporal" in the sense of animated GIFs 
etc. where temporal control etc. is not expected or desired.  They 
probably do not have associated audio, perhaps?

That means that a 'static' SVG image is indeed an image, whereas an 
SVG presentation that has 'significant' temporal behavior is video.

I'm not sure what to say about interactivity;  SVG allows it, so 
probably it's allowed.  But then, why isn't an HTML page embeddable 
in image?  It has a visual representation, and if we allow 
interactivity, it would seem to fit.

Similarly using SMIL to layup something that was 'static' (perhaps 
several images overlayed in regions) would seem to also be allowed.

Hm.  More principles, someone?
David Singer

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