Great post Frankie, and very clever and informative.
Thanks for sharing.

Best, Cristiano


On 17 Aug 2009, at 18:11, Frankie Roberto wrote:

> On Mon, Aug 17, 2009 at 11:59 AM, Jon Pratty <[log in to unmask] 
> >wrote:
>
>
>> My query today is about Alt tags.
>>
>
> I didn't want to go all geek on everybody, but nobody else has  
> responded to
> this yet, and it's something that there's still a bit of confusion  
> about, so
> I'll give it ago. If you're not interested, or already know this  
> stuff, look
> away now...
>
> Okay, so the alt tag (more precisely called an attribute) is meant to
> represent an textual "alternative" to the visual content (the photo or
> image). That is, if someone can't see the image, either because they  
> are
> blind, visually impaired, or because they're on a flaky or slow  
> internet
> connection, or because the image isn't available due to a broken  
> link, or
> because they're offline and only have access to the text (eg if  
> using an RSS
> reader which only caches the text for offline use, such as Google  
> Reader) or
> finally because they've simply chosen not to display images (rare,  
> but might
> happen for example on a mobile phone if someone wanted to save  
> bandwidth
> costs, or to just make pages load quicker)...
>
> ... then the text in the alt attribute is displayed INSTEAD of the  
> visual
> image.
>
> This is an important point, as it means that you show only ever see  
> the
> visual content OR the alt text, never both at the same time. So the
> behaviour of Internet Explorer prior to version 8 was 'wrong' in the  
> sense
> that it displayed the alt text as a tooltip. To appreciate why this is
> wrong, consider the instance where you have an image containing your  
> logo,
> which consists of the name of your museum (eg "The Hat Museum") in a
> particular font or wordmark. Wherever possible, you'd want people to  
> see
> this in the graphic form, as it's part of your brand identity, but  
> if that's
> not possible, then people should just see the name in plain text. So  
> the alt
> text is simply "The Hat Museum". So the behaviour of old versions of
> Internet Explorer in showing the alt text as a tooltip meant that  
> people
> hovering over the logo got the same text as was written in the logo  
> - not
> very useful.
>
> So far, this is all pretty represents the consensus of best  
> practice, and
> the fact that Internet Explorer 8 has changed its behaviour shows  
> that it's
> the way to go.
>
> What's less understood is what the alt text should be for images like
> photos, or illustrations, or graphics which serve a purely aesthetic
> purpose.
>
> If, for example, you write a blog post featuring an interview with  
> somebody,
> which contains a photo of the person you've interviewed, what should  
> the alt
> tag be on that photo. Some people might include something minimal like
> "Photo of <person's name>", which isn't very helpful at all. Other  
> people
> might try to be a bit more descriptive and say something like "Photo  
> of
> <person's name> posing in <location> with a laptop and a cool pair of
> shades". On the one hand, this is giving you the information which  
> someone
> who can see the photo is getting. However, the location, the laptop  
> and the
> cool shades probably aren't relevant to the story you're telling in  
> the blog
> post (in linguistics-geek-speak, it's not the "overtly intended
> communication"). So in this example, to work out what the optimal  
> alt text
> should be, you have to work out what the photo is actually  
> communicating.
> It's probable that it's not actually communicating much at all -  
> simply
> giving you an idea of what the person looks like. In this case the  
> alt text
> should be blank - ie alt="". This means that people who can't see  
> the image
> just get the text, with nothing else present - not an identical  
> experience
> to those who can see the image, but an equivalent one.
>
> On the other hand, there may be instances where a photo of a person
> communicates something which is central to the understanding of a  
> web page.
> For instance, you may write a "mystery object" type blog post, which  
> shows a
> curator holding an usual object, along with some text asking people  
> to guess
> what the object is. What should the alt text be here? Well, if you  
> left it
> blank, anyone who can't see the object is pretty left out from the  
> whole
> experience. On the other hand, if you described the photo fully in  
> the alt
> text, eg as "A photo of museum curator <person's name> holding an old
> medical instrument called an 'Earoscpope'" - then you're also giving  
> people
> who can't see the photo a poorer experience, as you're giving the  
> game away
> and are telling them exactly what it is. So in this example, a  
> better alt
> text would be something like "A curator holds a small metal object,  
> about
> the size of her palm, which at one end has a nut and screw, at the  
> other end
> has a small, curved protruding brown tube, and at the bottom has a  
> small
> wooden knob". This gives people who can't see the photo an  
> experience which
> is a little more equivalent to those who can (depending on how good  
> you
> think my description is), and they can still participate by guessing  
> what
> the object might be.
>
> So that's how alt text is meant to work. In practice, however, very  
> few
> people have this level of understanding about what good alt text  
> should be,
> and even amongst those who do, very few people take this amount of  
> time to
> properly consider the meaning of an image and to craft an equivalent
> text-based experience. This is compounded by the fact that very few  
> CMSs
> implement alt text in a way that supports this kind of considered  
> usage (eg
> by limiting the amount of characters you can use, or by associating  
> the alt
> text with the image, when the same image can communicate different  
> things in
> different contexts). Plus you also have to consider sites like  
> Flickr, where
> millions of photos are contributes by ordinary people, and it's hard  
> enough
> to get them to title and tag the photos, let alone write alternative  
> textual
> versions.
>
> For this reason, the current HTML 5 specification (
> http://www.whatwg.org/specs/web-apps/current-work/#alt) makes a  
> distinction
> between a blank alt attribute, which means roughly "this image is  
> decorative
> and doesn't communicate any content", and a missing alt attribute,  
> which
> means roughly "this image does communicate something, but we are  
> unable to
> tell you what". This latter case is obviously not ideal from an
> accessibility perspective, but at least it's honest, and in  
> circumstances
> like Flickr, is really the only option.
>
> So my general advice is to try to write meaningful alt text whenever
> possible, and to train other people to do so, but where this isn't  
> possible
> (due to time, resources, CMSs issues, whatever), acknowledge your  
> failings
> by not specifying an alt attribute at all...
>
> Phew!
>
> Cheers all,
>
> Frankie
>
> P.S The mystery object I described above is actually featured on this
> Powerhouse Museum blog post:
> http://www.powerhousemuseum.com/collection/blog/?p=436, where the  
> alt text
> is simply "Earoscope", (although this name is also given in the blog  
> post,
> along with a reasonable description, so perhaps the alt text should be
> blank?).
>
>
> -- 
> Frankie Roberto
> Experience Designer, Rattle
> 0114 2706977
> http://www.rattlecentral.com
>
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