Information Communication Technology (ICT) Images

Images need to provide alternative text (also referred to as “alt text”) for accessibility. Alternative text is a textual substitute for non-text content.

Image Alternative Text Serves Several Functions:

  1. Screen readers announce alternative text in place of images, helping users with visual or certain cognitive disabilities perceive the content and function of the images.
  2. If an image fails to load or the user has blocked images, the browser will present the alternative text visually in place of the image.
  3. Search engines use alternative text and factor it into their assessment of the page purpose and content.

Images Can Enhance Comprehension

  • It’s easy to assume that images are bad for accessibility, since alt text essentially replaces images with text for users that cannot perceive images.
  • The logical extension of that thought is that text-only sites are ideal for accessibility.
  • However, that logic is flawed—many people can greatly benefit from images while screen reader users are presented with a “text-only” version through appropriate alternative text.
General Information Image Types Complex Images Data Visualization Platforms
  • Alt text should be a maximum of 150 characters or roughly 30 words.
  • Alt text should not be redundant or provide the same information as text near the image.
  • Do not include phrases like “image of …” or “graphic of …”, etc. This is redundant since screen readers already announce “graphic” along with the alt text. If the fact that an image is a photograph or illustration, etc. is important content, it may be useful to include this in alternative text.
  • Assistive technology devices (like screen readers) have limited reading control within long alt text (can’t pause, stop, or easily resume reading if interrupted)
  • See the complex image accessibility guide for other text alternative options when handling complex images.

Types of images

  • Informative images:
    Pictures, photos and illustrations of people, scenery or objects.
  • Images of text:
    Logos, some complex images
  • Decorative images:
    Decorative icons, horizontal lines
  • Functional images
    Image used as a link or button like a print, delete or email icon.
  • Complex images:
    Charts, graphs, maps, infographics, dashboards (data visualizations)

complex images


Complex images, also known as “data visualizations”, include examples like: Charts, graphs, infographics, dashboards, dynamic and static maps.

Tableau Visualizations

Microsoft Power BI Visualizations

DYNAMIC MAPS

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