Images can cause barriers to people with disabilities. Depending on the audience, a website can fail to convey its meaning when relying on inaccessible images.
Adding accessible images to a website can improve the user experience for all. Consider the following types of users to better understand their experience with images on websites.
- People with cognitive and learning disabilities: Images and graphics make content easier to understand.
- People using screen readers: The text alternative can be read aloud or rendered as Braille.
- People using speech input software: Users can put the focus onto a button or linked image with a single voice command.
- People browsing speech-enabled websites: The text alternative can be read aloud.
- Mobile web users: Images can be turned off, especially for data-roaming.
- Search engine optimization: Images become indexable by search engines.
Only use images that serve a purpose. When in doubt, it’s best to sacrifice beauty for accessibility and usability.
Always include alternative (alt) text
All images must include alternative text that can adequately portray the content or function of the image.
- Be descriptive and brief in presenting the same content and function of the image as clearly as possible.
- Don’t be redundant. If the same information is provided within the text of the document, use, “” (empty apostrophes) as the alt text so that the screen reader skips that image.
- Don’t use the phrases “image of” or “table of” as this is usually clear to the user.
- Don’t use quotation marks or apostrophes within alt text, as screen readers will interpret these punctuation marks as the end of the alt text, and read them aloud as HTML characters.
Alt text for complex images
Alt text is an essential component of accessibility but sometimes a graphic or visual component is too complex to be adequately explained in character-limited alt tags. Examples of complex images include:
- Graphics and infographics
- Graphs, tables, and diagrams
- Maps
- Images with substantial information
If you can’t clearly describe an image within the alt text’s character limit or in the text, you will need to create a separate (accessible) document or webpage with a “long description” of the image. Long descriptions provide blind and low-vision readers with more comprehensive and meaningful information about a complex image.
They contain a breakdown of every important element in a complex image including the text in the visual, and a description of any graphs or charts and interpretations of data that can be inferred from charts or tables. Add alt text to briefly describe the image and identify the location and link to the long description.
Learn more about how to add alt text to complex images
- Alternative Text, WebAIM
- Complex Images with examples, W3C
- Write good Alt Text to describe images, Harvard University
Learn more
Images Concepts tutorial, W3C WAI
Do you work for the City of Portland? Use our resources on the employee intranet.