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

RE: Request for review of alt and alt value for authoring or publishing tools

From: Ian Hickson <ian@hixie.ch>
Date: Tue, 15 Apr 2008 21:14:16 +0000 (UTC)
To: John Foliot <foliot@wats.ca>
Cc: 'Tomas Caspers' <tomas@tomascaspers.de>, wai-xtech@w3.org, wai-liaison@w3.org, public-html@w3.org, 'HTML4All' <list@html4all.org>
Message-ID: <Pine.LNX.4.62.0804152102530.29828@hixie.dreamhostps.com>

On Tue, 15 Apr 2008, John Foliot wrote:
> Ian Hickson wrote:
> > 
> > Right, because the UA/AT is in a much better place to know how to help 
> > the user in these cases. The idea here is to help the user.
> Then start by giving the user something that their AT can work with.  
> You are handing them a vacuum and saying figure it out.  Ian, there is a 
> picture on my desk, what is it of?  You are asking AT to play "Is it 
> bigger than a breadbox" and then not answering any of the questions.

There is *absolutely no practical difference* to the UA between omitting 
the alt="" attribute altogether, and having the alt="" attribute set to 
some magical reserved value. They are functionally identical, and user 
agents can get as much information from either.

> But in this particular case, the spec is excusing a key player (the 
> authoring tool/web-app) from it's role in ensuring that the playing 
> field remain level.  You are saying "we can't come up with a solution, 
> so AT needs to do so" while at the same time giving AT *absolutely* 
> nothing to work with.

The server has nothing to work wither either. None of the players here 
have anything to work with. It sucks, but that doesn't make information 
magically appear out of nowhere.

> > We can get better accessibility by letting user agents compete on best 
> > handling of these images than we can by letting servers, who have near 
> > zero motivation to address this issue, try to come up with some 
> > half-baked solution.
> But if the servers *must* provide part of the solution (to be 
> "conformant" servers) you have given them the motivation.

Well, we can test that now, can't we? Since HTML4 require the alt="" 
attribute, your argument is that servers have the motivation to include 
alternative text on images for which the user has not included any 
alternative text.

So let's look at a random image on Flickr:


What's the alternative text on the critical image?:

   <div id="photoImgDiv854359279" style="width:502px" class="photoImgDiv">
   <img src="http://farm2.static.flickr.com/1378/854359279_73592d7334.jpg?v=0" 
   alt="" width="500" height="375" onload="show_notes_initially();" 

The empty string! That's the single _worst_ value you can give in this 
case. What we learn from this is that requiring alt="" attributes on 
images ends up motivating the servers _to lie_. They say the image isn't 
important, that it's decorative, when in fact it is the single most 
important piece of information on the page.

> > Reserved values are just syntactic variants on omitting the attribute. 
> > There is no practical difference. (Well, other than reserved values 
> > being significantly less usable in today's UAs, and omitting the 
> > alt="" attribute being cleaner, which is why the spec says to omit the 
> > attribute instead of inventing some new reserved value.)
> Yes and no.  Reserved values can be programmatically assigned whatever 
> values/uses a user-agent needs or wants.  By using a reserved value, AT, 
> all AT not just a particular flavor or brand of AT, can parse the value 
> and say "oh, one of those... I do this with those" consistently. While 
> there is a weak semantic value to a reserved value, there is *some* 
> value, whereas the vacuum of not having any alt value is just that, a 
> vacuum, and asks essentially for a guess, without providing *ANY* clues.  
> Visual users can see the photo, non-visual users are discriminated 
> against by being handed nothing.

This is incorrect. There is absolutely no practical semantic difference 
from the UA's point of view between an omitted alt="" attribute when 
omitting hte attribute is defined to mean "the image is critical but has 
no content" and a special reserved value which is defined to mean "the 
image is critical but has no content". It is merely a syntactic detail.

>   "Whatever the device you use for getting your information out, it 
> should be the same information." - TBL
> ...suggests to me that it should *not* be the final consuming user-agent 
> that must deal with the problem (end of the supply chain), but rather 
> the author and authoring tools (beginning of the supply chain) - it's 
> the old adage: garbage in = garbage out and nothing within the spec 
> currently contradicts or corrects this problem.

We all agree that the authors should include alternative text.

Why don't you include alternative text for the images on your Flickr 
account? You could easily add a comment to each image describing the photo 
for the benefit of blind users. Why don't you?

And if _you_, an accessibility expert who cares about blind people, don't 
bother to include descriptions of photos you upload to Flickr, how can we 
possibly expect Random Joe User, who frankly _doesn't_ care about blind 
users, to write descriptions for Flickr to include?

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 15 April 2008 21:15:12 UTC

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