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

Re: alt and authoring practices

From: Smylers <Smylers@stripey.com>
Date: Sun, 4 May 2008 02:44:40 +0100
To: "HTML Working Group <public-html@w3.org>" <public-html@w3.org>
Message-ID: <20080504014440.GD11992@stripey.com>

Robert J Burns writes:

> Descriptions of the photograph in this scenario do not belong in the
> alt attribute. This is a fundamental misuse of that attribute

Why?  The purpose of the alt attribute is so that those who don't see
the image get an alternative experience which (so far as the medium of
text permits) makes up for the lack the image.

To be a true 'alternative' it should surely be such that the information
gleaned is as close as possible whether looking at the image or reading
the alt text.

In the case of a photo which users with images will look at and see
something relevant to the page, it therefore makes sense for the alt
attribute to explain that in words.  Anything less than that and users
without images are missing out.

> The description metadata for a photograph properly belongs in the
> media file's metadata or pre-extracted by the author and authoring
> tools and placed in a referenced document fragment (referenced either
> with longdesc or aria:described-by attributes to name a few).

That's begging the question.

> Filling the alt attribute with descriptions of a photograph is
> inappropriate.

Why?  What else would the alt attribute have?

> To summarize:
> • @alt: a textual alternate, indispensably substituted for the image in 
> cases where the user or user agent is unable to retrieve or otherwise 
> consume the resource

Sounds about right.

> • media format metadata: for descriptions, titles, coverages, copyright 
> notices, licenses, etc. (ideally UAs would make some or all of this 
> available to users in browsing situations)

OK.  None of that needs to be in alt (unless that's what somebody
viewing the photo would see).  However this is made available it should
work for both image-viewing and image-less users.

> • document fragment referenced through @aria:described-by or @longdesc: a 
> good place for authors and authoring tools to extract a description of 
> the photograph for user agents unable to do it themselves

I'm unconvinced of the reason for having this, but if it exists then it
is surely supplemental to the alternative text (otherwise the alt text
isn't a genuine alternative)?

> So much of the talking past one another is due to some trying to make
> @alt serve all of these roles and therefore making it mandatory is
> cumbersome.

Not at all.  alt quite simply should be an alternative way of conveying
(as far as possible) the same information; nothing more, nothing less.

> Imagine a situation where I ask a vision impaired colleague to download 
> the image from my iPhoto web gallery: ‘IMG_0301’.

Imagine you ask a sighted colleague to download IMG_0301; how would she
know which photo is IMG_0301?  Presuming that the photo in question
doesn't have "IMG_0301" as part of the visible image, in order for a
sighted user to find it that label must be used somewhere in the site --
either as text visible on the page, or in a title attribute (or perhaps
just in a URL).

> What text alternates would be required for such a vision impaired (or
> totally blind) user to perform such an operation.

None: he could use exactly the same information as the sighted colleague

> What allows the user to view the download the photo is properly
> provided alt text: 'view image &quot;IMG_1234&quot; fullsize'

No, that just duplicates the information which is available elsewhere,
for both those with and without images.

> (BTW, I know my galleries include the title of the photo anyway, but
> that's an optional checkbox in iPhoto since some users do not want
> those cryptic looking titles marring the page).

If they were omitted then user seeing images wouldn't be able to locate
a photo by its filename.

Received on Sunday, 4 May 2008 01:45:30 UTC

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