[whatwg] Proposal for an addition to the authoring guidance regarding the alt attribute

[Ian Hickson]

On Tue, 3 Aug 2010, Markus Ernst wrote:
>
> Section 4.8.1.1.9 describes how alternative text for content images 
> should be written: 
> http://www.w3.org/TR/html5/embedded-content-1.html#a-key-part-of-the-content

(Note that the /TR/ copy is very out of date. I recommend using the 
dev.w3.org copy or the whatwg.org/html5 copy.)


> Then, there is a general guideline about writing alternative texts in 
> section 4.8.1.1.12: "A corollary to this is that the alt attribute's 
> value should never contain text that could be considered the image's 
> caption, title, or legend. It is supposed to contain replacement text 
> that could be used by users instead of the image; it is not meant to 
> supplement the image. The title attribute can be used for supplemental 
> information."
> 
> IMO the wording of 4.8.1.1.9 is somehow contradictive to the general 
> guidance in two cases:
> 
> 1. The image is the information itself, it does not convey any 
> information beyond it's visuals. This is a very common case, for example 
> in photo galleries. Unlike the examples given under "The general case" 
> (where lack of the image is lack of information), the images in a 
> wedding photo gallery cannot be described in a way that matches 
> 4.8.1.1.12 and provides any useful information for e.g. a blind user. 

Sure they can. It's certainly not easy or quick to do so, but it's 
possible.


> The information "Me, Gary, and his parents eating the cake" is rather 
> useful for those who actually see the image, and should go to the 
> caption, as correctly stated in 4.8.1.1.12.

Agreed.


> 2. The image illustrates what is discussed in the surrounding text, or 
> has a caption describing it. Inserting alt text would actually duplicate 
> the information, but not convey anything useful for those who don't see 
> the image. IMO alternative text should be omitted in this case (as e.g. 
> Wikipedia does: http://en.wikipedia.org/wiki/Squirrel - the alt 
> attribute values of all content images are empty).

That's "A graphical representation of some of the surrounding text", which 
is an earlier section.


> So I propose to:
> - Explicitly treat these two cases in 4.8.1.1.9, requiring to insert no alt
> text there

On the contrary, alt text should be given for the first case. The second 
case is already handled in a more specific section (and indeed requres 
empty alt="").


> - In the part "Images whose contents are not known", remove the word
> "unfortunate" at the beginning ("In some cases"), and the first note.

I disagree; it is unfortunate.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'