Course Accessibility Checklist: Long Descriptions

Using Long Descriptions

• Long descriptions are necessary when complex images, diagrams, graphs, and charts require more explanation than you can provide in the alternative text area.
• Long descriptions function as a replacement for all the visual information conveyed by the diagram, graph, or chart.
• When you use a long description, the alternative text for that image should be a brief summary of the information that will follow in the long description. 

Tips for Writing Good Long Descriptions

• Long descriptions should be used when text alternatives are insufficient to answer the question "what information is the image conveying?"
• In some situations, the information being conveyed will be how an image looks (e.g., an artwork, architectural detail, etc.). In these cases, try to describe the image without making too many of your own assumptions.
• One approach is to imagine you are describing the image to a person over the phone.
• Ensure that you still provide concise alternative text to help readers decide if they are interested in the longer description

Complex images such as charts, graphs, diagrams, and maps need long descriptions to ensure that the visually impaired student has access to all the information provided in the image.  The long description serves as a replacement for the image so it must be more that just a description of the image.  

Because various screen readers react differently based on the type of document (word, Blackboard content, PowerPoint, etc.) a safe practice is to include long descriptions of complex images in the actual document.  This ensures that the visually impaired person can access the information, and it provides support for all viewers of the document. Some sighted persons have problems interpreting complicated graphics so including the long description in the text benefits everyone.   

When you include a long description of an image in the text you will still need to enter some alt text.   You could actually use something like "Information about the image is included in the text under the image."  The screen reader will  alert the blind person that there is an image and let them know where the description of the image is.