- From: Leif Halvard Silli <lhs@malform.no>
- Date: Wed, 16 Apr 2008 01:16:36 +0200
- To: Ian Hickson <ian@hixie.ch>
- CC: John Foliot <foliot@wats.ca>, "'Tomas Caspers'" <tomas@tomascaspers.de>, wai-xtech@w3.org, wai-liaison@w3.org, public-html@w3.org, "'HTML4All'" <list@html4all.org>
Ian Hickson 08-04-15 23.14: > On Tue, 15 Apr 2008, John Foliot wrote: > > Ian Hickson wrote: > > > 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. > There ought to be several things to work with on the page you provided below: The image caption, the name of the user, date/time, title of the photostream. > > > 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="" > HTML 5 gives many examples. That is an improvement. It is not only demanding that matters, but showing the way as well. > 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: > > http://flickr.com/photos/18356286@N00/854359279/ > > 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();" > class="reflect"></div> > > 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. > > 20 of 26 images all together have alt text and are just site stuffing. (And 4 of the <A> elements also have alt attributes ...). The 6 other images have emty alt. At least half of those 6 belong to the user/reader generated content/stream. So, there is a some kind of pattern there. If thoe images could have meaningful text, it would matter. > > > 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. > I agree that there is no practical semantic difference then. And for the sake of semanticness, it could be possible to define several equally bad/good solutions. (Some migh prefer no alt, som an alt with a reserved word, others would prefer enumeration.) But there might be a practical user experience difference, depending on what the user agent is prepared to make something out of. -- leif halvard silli
Received on Tuesday, 15 April 2008 23:18:03 UTC