Writing alternative text (or an image description) for graphics, charts, diagrams, and other media that may be important to convey a message or inform users has now gotten a littler easier. The National Center for Accessible Media has added a new resource that will specifically help faculty with examples they typically post on lecture and test materials: Item Writer Guidelines for Greater Accessibility.
Oftentimes, accessibility and usability come hand in hand. While these guidelines are intended to assist users with visual disabilities, they can also assist faculty on designing test items or materials that are easier for users with other disabilities (or none at all) to understand and interactive with.
And, in general, they are a good resource for graphics usage on all websites and electronic materials.
I've included it and some of their other resources on the Web Accessibility website, under Agencies/Organizations, for your use. Please check this website periodically for new resources.
As a reminder for all Cascade Server users, we still have useful information on graphics in our CMS Tutorial: Tips and Tricks site that we have not moved over to our blog: