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General Checkpoints - Checkpoint 1.1

Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video.

http://www.w3.org/TR/WCAG10/

Guideline

Provide equivalent alternatives to auditory and visual content

Why?

This is to ensure that people using text-only browsers or screen-readers or people who browse with images turned off can still access all the information in the web site. Text alternatives of audio files assist people with hearing impairments and allow the content to be accessed by a search engine. In some cases it is necessary to add a caption to the image. For graphs and diagrams it is important that the key points are described within the accompanying text.

ALT attributes should describe the function of the image, not describe the image itself. If an image is purely ornamental (i.e. a spacer GIF), and has no other function then the ALT attribute should reflect this. In this case the ALT attribute should be:

<IMG SRC=”image.gif” height=”15” width=”10” ALT=“ ”>

Note that if the ALT attribute is empty (e.g. ALT=“”) then some screen-readers will read the SRC tag of the image. Thus it is important that the ALT attribute contain a space.

This toolkit provides information about making images and image maps accessible.

Example

An example of difficulties between an alternative description and an equivalent description can be illustrated below. The ALT attribute for this cartoon on the Better Health Channel is ‘A Tandberg cartoon’ – it does not actually describe the image.

In this case a ‘long description’ would be beneficial. These links are recognised by screen-readers, but are not available through IE or Netscape browsers. Please note that D links are deprecated in favour of the LONGDESC attribute. TITLE attributes should also not be used with the IMG tag.

Tandberg cartoon

Permission to reproduce this Tandberg cartoon provided to Multimedia Victoria (2002)


To create a ‘long description’:

<IMG SRC=”tandberg.gif” height=”15” width=”10” ALT=“A Tandberg cartoon” longdesc="tandberg.html">

Then you will need to create a file named ‘tandberg.html’ with text similar to the following:

Tandberg cartoon: Man slumped in front of the TV while a woman gestures to the computer on the other side of the room labeled ‘Better Health Channel’. Man says “I can’t walk that far.”

How to test

  • Use Cynthia Says to ensure that all images have ALT attributes and audio files have text equivalents [Compulsory]
  • Using the IE Accessibility Toolbar or the Firefox Developer toolbar replace images with their ALT attributes and make sure that the ALT attribute is equivalent to the image [Compulsory]
  • Manually browse through the site with all the images turned off and see if you can still navigate around the site and access information easily [Optional]
  • Manually test that all information is available in text by browsing the site with graphics and plugins turned off or view the site in the text-only browser Lynx [Optional]
  • User test the site with a blind or visually impaired person who is a competent screen-reader user [Optional]

Techniques for addressing Checkpoint 1.1

Added: 23 July 2007 Page views: 5,187 Rating: 0 Votes: 0
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Last updated: 23 July 2007