Description strategies vary depending on the type of image being described. View these examples for ideas on how to describe charts and diagrams. For the purpose of this page, long descriptions are just shown on the page and not in a show/hide link. At the end of this module we will explain how to add long descriptions in Evolution and Canvas.

Example 1: Pie Chart

For pie charts, a good method to use is a drill-down technique, in which a brief summary of the image is followed by an extended description and specific data in list or table format. If a single category is associated with more than one value, such as a percentage and a dollar amount, use a table instead. Either way, data should be ordered from general to specific. Doing these things lessens cognitive load by allowing users who can't see the image to more easily form a mental picture. The alt text for this image is "Pie chart of 2011 smartphone sales described below."

This example shows a pie chart with its corresponding accessible long description.

Pie chart of 2011 smartphone sales described below — Figure 9. U.S. Smartphone (Adapted from Forbes, 2011

Long Description:

A pie chart showing 2011 U.S. smartphone sales by phone type:

iPhone: 22%
Motorola: 20%
HTC: 17%
BlackBerry: 15%
Windows Phone: 12%
Nokia: 10%

Takeaway: The description for a chart can include a list or table.

Example 2: Process Diagram

Diagrams that illustrate a process have a very different purpose from data-based diagrams like charts, so making their descriptions accessible requires a different approach. Processes that are presented visually can be described using outline lists. Some types of STEM process images that work well in a list format include flowcharts, diagrams, and illustrated chemical reactions.

This example shows an accessible long description for the flowchart in Figure 10; it includes a short general description with an outline list providing the details. The alt text for this image is, "Decision to go shopping flowchart described below."

Decision to go shopping flow chart described below — Figure 10. Grocery-Shopping Decisions Text Alternative

Long Description:

The figure is a flowchart that illustrates the process of deciding whether to go grocery shopping or not. It starts with the question "Should I shop?" and moves through conditional questions to arrive at a conclusion.

Should I shop?
- Transition to Do I need food?
Do I need food?
- No. Transition to No.
- Yes. Transition to Do I have transport?
Do I have transport?
- No. Transition to No.
- Yes. Transition to Do I have money?
Do I have money?
- No. Transition to No.
- Yes. Transition to Am I too hungry?
Am I too hungry?
- No. Transition to Yes.
- Yes. Transition to Eat.
No
- End of decision, answer to go shopping is No.
Eat
- Transition to Yes.
Yes
- End of decision, answer to go shopping is Yes.

Takeaway: A flowchart can be described using a list.

Updated September, 2020