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Re: Information access for all : img, object and @alt

From: Robert J Burns <rob@robburns.com>
Date: Tue, 6 May 2008 12:28:11 +0000
Cc: "public-html@w3.org" <public-html@w3.org>
Message-Id: <0D634B1C-0B48-480F-88A3-A4130BE45636@robburns.com>
To: "Olivier GENDRIN" <olivier.gendrin@gmail.com>

Hi Oliver,

To sum up, in a perfect world CSS would handle every use case for that  
alt attribute. Understanding that sentence is the key to understanding  
the semantics of the alt attribute. Other descriptive metadata belongs  
elsewhere, but I'll elaborate further below.

On May 6, 2008, at 11:32 AM, Olivier GENDRIN wrote:

>
> I'm wondering why we have so passionate discussions about img and
> @alt, and none about the alternatives of object, audio, video. The
> uses cases are the same : giving access to the information unavailable
> to some person/UA/thingy trough alternatives.
>
> Maybe we should first have a global policy about informations
> alternative before having a casus belli about one of the aspects (even
> if it's the most wildly used).
>
> We had an example about pictures gallery on flickr, what about video
> gallery on youtube ?

I appreciate the sentiment: a sentiment I once tried to make myself.  
However, I think it glosses over the particular uniqueness of the way  
the IMG element is used (compared to these others) and the unique way  
the alt attribute is meant to provide ONLY the indispensably crucial  
information about the embedded content in those circumstances.

The information alternatives for the other embedded content elements  
is more akin to the role played by the longdesc attribute on the IMG  
element than the alt attribute. This other content mechanisms is more  
intended for visual, aural and subject descriptions of the media. On  
the other hand the alt attribute plays a particularly special role  
(along with the IMG element in these cases) of providing textual  
information about how the embedded image is being used.

The clearest example of this is where rich text is needed for the look  
of a page. Perhaps an invitation to a special event with frilly  
cursive writing. The designer of the page is not confident that the  
font deployed for this text will be reliably downloaded by all of the  
user agents and environments that might make use of this site. So the  
designer turns to the use of images depicting rich text. So in the  
image that says “You're are cordially invited” in cursive writing, the  
alt attribute needs to be:“You're are cordially invited” . Likewise  
for he remaining images of text. As CSS improves with CSS3 and support  
for CSS improves (especially the Font Face module), hopefully CSS can  
take over the role played by these images. It is not hard to imagine a  
World where CSS could satisfy every need currently handled through the  
alt attribute.

While someone might use an OBJECT element or an EMBED element in the  
same role (and if we feel HTML5 should accommodate that we should  
certainly add the alt attribute to those elements), the IMG element is  
typically the one used for such use cases. It is these particular uses  
of an image that requires the alt value to be non-blank. In most other  
cases, the best practice is to include alt='' and then reference a  
document fragment described in the photograph or image otherwise  
referenced by the longdesc attribute.

To sum up, in a perfect world CSS would handled every use case for  
that alt attribute. Understanding that sentence is the key to  
understanding the semantics of the alt attribute.

Take care,
Rob
Received on Tuesday, 6 May 2008 12:29:10 GMT

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