When “Alt Text” is not Enough

by Janice Florent

Computers can read text on a screen but images, graphs, and charts are meaningless to visually impaired users. Alternative text (alt text) is an alternate method for supplying information about images, graphs, and charts to users who are visually impaired.

Adding alt text to images, graphs, and charts is an important part of making them accessible. Most images, graphs, and charts can be made accessible using alt text descriptions. However, complex images, graphs, and charts require more detailed description than the limited one or two brief sentences that are used in the alt text.

Examples of complex scientific images

What should you do when you have a complex image, graph, or chart whose meaning cannot be conveyed with alt text alone? There are several ways to handle complex images where a short description is not possible. The best solution is to include a thorough description of the complex image in the content of the page, immediately before or after the image. If you don’t want to add more content to your page, another preferred alternative is to create another web page with the thorough description of the complex image and link to it near the image.

You may be wondering what exactly should you include in the thorough description. The Diagram Center (Digital Image And Graphic Resources for Accessible Materials) is an excellent resource that provides comprehensive guidelines to make it easier for you to make complex images accessible to all learners.

Here are a few additional resources to help you with describing complex images:

• Effective practices for description of science content
• How do we access meaning in art? (Describing art images)
• Open University's guidelines for describing visual teaching materials

It is extremely important for students with disabilities to have access to accessible course content. Describing complex images utilizing these tips is good course design. Even though you may not have a student with a disability currently enrolled in your course, you will find students without disabilities will take advantage of accessible content as well.