Making Images Accessible

An image description is used to convey the information contained in an image to a person who cannot access it in its original form.

It is essential that blind and partially sighted users receive the same information as their sighted peers. Including an image description will enable users to:

  • achieve the learning outcome intended by the author
  • participate in discussions based on the information within the image

What Counts as an Image?

Images include graphs, charts, diagrams, photographs, illustrations and artworks. They also include mathematical equations, chemical formulae, musical notation and special symbols, as a screen reader will not be able to access these to read them aloud. 

an example of a chart, graph, mathematical formula, and diagram that would need additional description if they added anything of use the viewer

Many blind and partially sighted readers use screen readers to access electronic materials on screen. If images do not have alternative text, a screen reader will pass over it, and the student will miss the information.

A person using magnification software to read printed material may struggle to see the details of an image and may only see a small part of an image at a time. An image overview will help them understand what is being shown. 

Do All Images Need Describing?

For practical purposes, the answer to this has to be "no." There are images which are decorative or summarize information in the text, and a description would not add anything of use to a blind or partially sighted user.

an example of a photograph that would need a description if it added information that a blind or partially sighted learner would need to know
An image needs describing if:

  • it contains essential information which is not readily accessible anywhere else
  • there is content or data within an image that needs to be conveyed
  • there is data within an image which needs to be interpreted
  • it is an image used as a basis for discussion
  • it is a visual summary of a long section which has no text summary
  • it introduces a type of diagram commonly used in the subject area
  • it is being used to teach how to use a particular type of diagram.

For charts, graphs and diagrams where the image summarizes data and other essential information: it is this data and essential information that needs to be described.

For images where a subjective response is required, or if the image is teaching a visual discrimination skill, then the appearance of the image will need to be carefully described.

If an image is purely decorative and adds nothing to the text, then a description may not be necessary; or depending on the context, a short note for example 'photograph of John Smith' will help a reader who has a small amount of vision to decide whether to spend time studying it with a magnifier.

Information on this page adapted from The UK Association for Accessible Formats.
"Describing images 1: General principles: Guidance from UKAAF." UK Association for Accessible Formats (UKAAF). June 2012. Web. 12 Nov 2014. <>.
Images from Microsoft Clip Art

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