Long Descriptions
Some images, such as diagrams, graphs, and charts, may require a longer description than what is recommended for the alt attribute (text in an alt attribute shouldn't be much longer than 125 characters). If the information in the image is included in the text on the page, you can simply add "image described on the page" in the alt attribute, and no other work is needed. But, for most complex images you will need to create a text alternative for the image that is provided in a show/hide link in Evolution or in a linked Word document in Canvas.
How to Write Long Descriptions
Writing long descriptions can be challenging. However, there are a variety of resources available to help you get started. Beyond the strategies, guidelines, and examples provided in this lesson, great training materials can be found at the POET Image Description site linked on this page, and you can always request assistance from an accessibility consultant if needed.
Strategies and Guidelines
An image description could be a straightforward text description, or it could be an HTML table, list, or some combination. For instance, bar charts convert nicely to data tables, and flowcharts can often be displayed as lists. The descriptions should not be more complicated than necessary and should be presented in a way that is easy to understand.
There are several strategies for writing longer descriptions, but here are some general principles:
- Start with a short general description, and then give details.
- Make descriptions as concise as possible without leaving out any key concepts or information.
- Use tables, lists, text, or some combination as appropriate.
Additional Training Resource
There is a nonprofit organization called Benetech Links to an external site. that is on a mission to use software and data to empower people to solve social problems. One of their initiatives is an excellent self-paced image-description training resource. Most of these links point to that resource:
- Alt Text Decision Tree Links to an external site.: This tool from the W3C will help you determine if you need alt text, a long description, or empty alt text.
- When to Describe section of the POET image training resource Links to an external site.: You can view different types of images to see when you would need to add a description.
- How to Describe section of the POET image training resource Links to an external site.: You will find explanations for what it means that the description fits the context, considers the audience, is concise, is objective, goes from general to specific, and more.
- Use the Practice Describing tool Links to an external site. to upload your own image and attempt to describe it.
- After you write your long description, have the subject matter expert review it for accuracy.