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Re: Request for clarification of the case where 'the image isn't discussed by the surrounding text, but it has some relevance'

From: James Graham <jg307@cam.ac.uk>
Date: Mon, 18 Aug 2008 14:25:28 +0100
Message-ID: <48A97848.8020703@cam.ac.uk>
To: Steven Faulkner <faulkner.steve@gmail.com>
CC: Ian Hickson <ian@hixie.ch>, W3C WAI-XTECH <wai-xtech@w3.org>, "public-html@w3.org WG" <public-html@w3.org>

Steven Faulkner wrote:
> The HTML5 spec currently states [1]:
> 
> "In some cases, the image isn't discussed by the surrounding text, but
> it has some relevance. Such images are decorative, but still form part
> of the content. In these cases, the alt attribute must be present but
> its value must be the empty string.

My understanding (and I'm sure someone will tell me if I am wrong) is that the 
current conformance requirements are designed so that the transformation
<img alt=$x> -> $x

preserves the semantics of the page (except in the case where x begins with { 
and ends with }) i.e. the meaning should be invariant under a script like

javascript:(function(){var%20img_nodes=document.getElementsByTagName('img');while%20(img_nodes.length)%20{var%20img%20=%20img_nodes[0];var%20replacement%20=%20document.createTextNode(img.alt);img.parentNode.replaceChild(replacement,%20img);}})()

(that should, in theory work as a bookmarklet, but I may have got something 
wrong, it is only very very lightly tested).

> So would the example below be non-conforming?
 >
> <h1>The Lady of Shalott</h1>
> <p><img src="shalott.jpeg" alt="Painting of woman in a small boat on a
> river in the countryside. A tapestry trails behind her in the water
> and there is a lantern, candles and a crucifix on the prow of the
> boat. She wears a white dress and has long loose hair."></p>
> <p>On either side the river lie<br>
> Long fields of barley and of rye,<br>
> That clothe the wold and meet the sky;<br>
> And through the field the road run by<br>
> To many-tower'd Camelot;<br>
> And up and down the people go,<br>
> Gazing where the lilies blow<br>
> Round an island there below,<br>
> The island of Shalott.</p>"

Given the design principle above, this is clearly non-conforming as it implies 
that the text

"Painting of woman in a small boat on a river in the countryside. A tapestry 
rails behind her in the water and there is a lantern, candles and a crucifix on 
the prow of the boat. She wears a white dress and has long loose hair."

is part of the poem. In this case it is likely that a user would figure out what 
is going on but in the case of a piece of prose or a play, alt text describing a 
decorative image could easily be confused with actual content of the surrounding 
piece.

-- 
"Eternity's a terrible thought. I mean, where's it all going to end?"
  -- Tom Stoppard, Rosencrantz and Guildenstern are Dead
Received on Monday, 18 August 2008 13:26:05 GMT

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