My Accessibility Check: Images and their Surrogates


This post is part of a series on my experiences with web accessibility. Each post condenses what I’ve learned from before and after as a real-life Vision Loser continuing 30 years of Internet use and as a new student of accessibility theory and practice. Sighted readers will learn a bit more about how a low vision persons uses the web and other Vision Losers may sense some of the rationale behind the annotation of graphics.

Why are ALT tags Rule #1 of web accessibility


Ok, so web pages are inherently visually motivated to exploit the power of browsers and graphic images to convey information to users. But does that mean that images can be used freely, for either decorative or information roles, without the slightest indication of their purpose on a page? Wouldn’t that be cruel to people without vision? Of course! And with increase in use of mobile devices with smaller screens, images may also be problematic for sighted people. And browsing without images showing remains common where bandwidth is limited by availability or cost. Hence, providing surrogates for images acquired the primary position in accessibility rule making.


Web standards make it implicit that web content should be perceivable necessitating alternative textual descriptions of graphics. That implementation of this rule is dead simple, to write a description as an accompaniment, denoted by the HTML identifier ALT.

Are ALT tags simple and easy to use?


Well, yes, it’s easy to add such tags. Creating web pages the power user way, with a Notepad, one adds ALT=”the description” to accompany the location , denoted by SRC, of the image. No big deal, but what would the description say? the color of the image? ithe who or where? the artful ambience? The trick here is that the ALT description should give exactly the information needed to place the image usefully in the context of the page, no more, and no less. Ouch, that requires thinking, like why have the image in the first place and what’s its role in the narrative of the page, in addition to attracting eyes and stimulating visual cortexes?


And, wouldn’t you know it, there are more messy questions as described in Web Accessibility Gone Wild from webaim.org. some images are purely decorative and some are used for layout of the page, neither of which require a real ALT description, which would only get in the way of screen readers. And there are charts and graphs where the data displayed is integral to the point of the web page. And some images just take a lot of words to describe. Furthermore, images are often associated with links where the descriptions overlap. Happily, the above article provides good commen sense practices for these situations.

Examples of Accessibility Issues for ALT and images


Images without ALT tags are often cited as “obstacles for the unsighted”, but this Vision Loser has only one experience like this. As described in previous post on “pie charts and literacy” inability to read a pie chart may have doomed my retirement funds during an analysis by my ‘Wealth Manager’. Not really, we’re all doomed, but inability to read the pie chart of asset allocations was a real bummer for me. The problem here is not so much that the pie slice relative sizes and labels were unavailable in a PDF document, but that I could not get my hands into the original data. Pie charts are not so much images as representations of data that stimulate questions about relationships within that data. I am still looking for the pie chart I can manipulate to get those relationships out of the data imprisoned in documents.


Generally, it does help to have image descriptions like ““bicyclists using curb cut in complex intersection” to force my brain into thinking about physical locations and moving objects. But rarely do I find the absence of a good description as a barrier to understanding the content of a page. With low vision myself, I don’t have much practice using images and ALT text, requiring a sighted helper to assure images are what they say.


On the other hand, now that I’m an accessibility advocate, it is annoying to find violations of Rule #1 because this may show a rather serious ignorance of or callousness toward accessibility. I recently found this in a left unnamed output of an NSF project on Broadening Participation in Computing. An excellent project to entice student interest in computing through a journalist pathway produced a newsletter with articles illustrated by images that read out to me as “497” and “2934”. All I could think of was a missed opportunity to raise the awareness of student authors about accessibility issues, like “how would your great-grandpa’s bad eyes read this page?” Our tax dollars should be properly used only when results are fully accessible. But don’t get me started on university and professional organization web sites!

What next for ALT?


Of course, there’s more to graphic media with Flash and animation. But the message of ALT seems to be:

  1. Leave off ALT tags if you want to put up a clear “No blind need apply” sign to your visiting potential clients and students.
  2. Put in the time thinking and checking out your web pages for image usefulness. Turn off images in your browser and see what’s missed. Do images still matter? Are they well supplemented by ALT descriptions?
  3. Decorative images may be vestigial ways of thinking about getting column 2 of text to start at position 43 when that’s going to interfere with text sizing requirements or be bungled in one or another browser. Or, even worse, really stupid cases are when a screen reader reads out “spacer, spacer” between words, indicating you didn’t know how to or care to test with a screen reader.
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2 Responses to “My Accessibility Check: Images and their Surrogates”

  1. desiree29 Says:

    Wow, this is a fantastic post on your experiences with the web as someone newly blind. Your insight and opinions are wonderful, thanks!!

  2. Webliography for ‘Grafting Accessibility onto Computer Science Education’ « As Your World Changes Says:

    […] AYWC Images and their surrogates — the ALT tag […]

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