Text Equivalents for Images and other Non-Text Objects

While ensuring accessibility does not mean that the web resource should avoid using graphical elements, it is important that all non-text elements are accompanied by text equivalents. Non-text elements are not accessible to users relying on speech readers and braille displays. Some users may use text-based browsers that do not support non-text elements, and some may have turned off support for non-text elements. Thus, text equivalents should be rendered in such a way as to effectively substitute non-text elements for variety of browsers and assistive technololgies employed by people with different disabilities. Text equivalents can also help all users find pages more quickly, since search robots can use the text when indexing the pages.
Non-Text Elements

Non-text elements that should be provided with a text equivalent include:

  • 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
  • video

Markup

Summary of Markup Associated with the Text Equivalents for Images and other Non-Text Objects Best Practices
Markup Spec Best Practice
Sub-Category
Description
a HTML4 Image Link
  • If a link contains an image, the image alt attribute value should contribute to describing the destination of the link
a HTML4 Media Objects
  • Links to resources that are video with audio must have synchronized text captions
  • Links to resources that are video must have descriptive audio
  • Links to resources that are audio must have text transcripts
area HTML4 Media Objects
  • Links to resources that are video with audio must have synchronized text captions
  • Links to resources that are video must have descriptive audio
  • Links to resources that are audio must have text transcripts
area[alt] HTML4 Informative Image
  • alt attribute on an area element should describe the target of the link associated with the link
area[alt] HTML4 Image Link
  • alt attribute should provide a description of the target of the link
area[alt] HTML4 Image Map
  • alt attribute of an area element should describe the target of the link
embed HTML4 Media Objects
  • embed element is not part of the W3C HTML 4 specification, but is commonly supported in browsers
  • embed elements that support video with audio must have synchronized text captions
  • embed elements that support video must have descriptive audio
  • embed elements that support audio must have text transcripts
img[alt] HTML4 Informative Image
  • alt attribute should provide a short description of the purpose and information contained in an image
img[alt] HTML4 Decorative Image
  • alt attribute should provide a short description of the purpose and information contained in an image
img[alt] HTML4 Image Link
  • alt attribute of an image that is a link should describe the target of the link
object HTML4 Media Objects
  • object elements that support video with audio must have synchronized text captions
  • object elements that support video must have descriptive audio
  • object elements that support audio must have text transcripts