W3C home > Mailing lists > Public > public-html@w3.org > May 2008

Re: alt text on Validator.nu image report (was: Re: alt crazyness)

From: Ian Hickson <ian@hixie.ch>
Date: Sun, 4 May 2008 07:31:11 +0000 (UTC)
To: Philip Taylor <pjt47@cam.ac.uk>
Cc: Robert J Burns <rob@robburns.com>, Henri Sivonen <hsivonen@iki.fi>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <Pine.LNX.4.62.0805040401490.15395@hixie.dreamhostps.com>

On Sat, 3 May 2008, Philip Taylor wrote:
> 
> So, the goal of the site's markup is to make sure the UA tells the user 
> clearly and concisely that there is an image here. It is up to the UA to 
> determine as much detail as possible about the image, and it is up to 
> the user to decide (based on context) that the image is important and 
> that it is worth looking at in detail.
> 
> In that case, <img src="..." alt="External image"> seems to achieve the 
> goal: as long as UAs do not ignore images with alt text, the user will 
> be made aware that the image exists, and can ask their UA for further 
> details.

Actually it doesn't, really. The intent of the alt="" attribute is to 
provide text that can be used to completely replace the image, and thus 
there isn't necessarily a way to distinguish this:

   <p><img src="x.png" alt="External image"></p>

...from this:

   <p>External image</p>

...in user agents that don't support images. In particular, a user agent 
like Lynx wouldn't distinguish the two cases above, but would show the 
image in the following case in a distinct UA-styled manner:

   <p><img src="x.png"></p>


> (My interpretation of the current HTML5 spec is that alt="External 
> image" would be non-conforming, because it does not serve as a 
> substitute for the image - it serves only as a marker for the image and 
> an indicator that the image is 'external'. The spec should not be so 
> strict in what the alt text must be, else it force sites like this to 
> compromise their user experience in order to achieve conformance.)

It is strict precisely to achieve a better user experience, as illustrated 
above.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Sunday, 4 May 2008 07:31:53 UTC

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