Re: HTML Action Item 54 - ...draft text for HTML 5 spec to require producers/authors to include @alt on img elements.

Hi Dave,

I hopefully will provide a clear answer to your question and at least  
for the two of us end the circle.

On May 12, 2008, at 4:14 PM, Dave Singer wrote:

> This entire conversation seems to be be in repeating circles.  
> Personally, I would like to see a considered answer to the question  
> below, and I don't think I have.  Having, in essence, the question  
> or disagreement endlessly repeated is making the mailing list  
> tedious to follow.  If we've had a helpful answer, can someone  
> repeat it?  If we're on track for getting an answer, can we wait for  
> it?  If we don't think an answer is possible, then we need to re- 
> frame the question.
> "In striving for the best support for accessibility, we would like  
> guidance on what to say in a specification on the use of the alt  
> attribute for an image when there is no reasonable alt text known.  
> It seems as if alt="" would state (probably erroneously) that the  
> image is not semantically significant, and alt="an image" -- or  
> something similar -- while true, is quite unhelpful.  Some of us are  
> uncomfortable with such a string, because it seems to mislead the  
> user agent into believing that there is useful alt text, when it may  
> be able to do better if it was aware that there is no alt text.  For  
> example, it can conclude quite easily by itself that it is "an  
> image" and in addition would be able to state its size, and would be  
> at liberty to do other analysis (e.g. stating that it had some  
> similarity to another image on the page, recognize that it contains  
> one or more faces, etc.).  It can also do this in the user's natural  
> language, if known.  Because of this, we have considered allowing  
> the omission of alt in this case (when no useful alt text is known  
> at the authoring point), but we are concerned about this too, as it  
> may 'open the barn door' and such a permission to omit may be  
> abused. In essence, we have three cases (useful text known, images  
> that are semantically insignificant, potentially significant images  
> with no known alt text) but only two indicators -- non-empty and  
> empty alt text?  Do you have guidance on what to say in a  
> specification on the use of the alt attribute for an image when  
> there is no reasonable alt text known?"

The alt attribute is only one specialized attribute for non-text  
media. For this case it should most likely be alt='' (for legacy  
reasons especially). However we have the longdesc attribute aria- 
described-by and potentially aria-role or similar attributes to  
provide the additional information needed. The alt attribute doesn't  
have to do everything.

So an image that is on the page but not part of a link, not presenting  
rich text, and not an icon  but still semantically important  would  
simply have alt=''. Perhaps something like this for a vacation  
photograph discussed on a blog:

<figure><legend>We made a sand castle a the beech</legend><img alt=''   
role='meaningful' longdesc='descriptions#sandcastle' ></figure>

Such an approach would:

1) satisfy the requirements you raised
2) provide rich accessibility
3) provide partial machine conformance verification
4) degrade gracefully in existing UAs
5) be easily generated from bulk upload authoring tools

I hope that answers the question satisfactorily.

Take care,

Received on Tuesday, 13 May 2008 10:44:02 UTC