Social Security Administration Guide: Alternate Text for Images

Purpose and function—missing the point

A description of an image in isolation from its context is not useful for a screen reader user. Consider the examples below:

 

“Pastel lays in the grass and waits for instructions.”
It’s missing the point. The text surrounding the picture is all about the harness. The purpose of the picture is to show the shape and nature of the harness. The alternate text does not properly convey the purpose of the image within the context of the surrounding text.

“Pastel with her guiding harness.”
It’s missing the function. A description of the harness is not given in the text surrounding the picture. The picture shows the viewer what the guiding harness looks like, so that is what should be included in the alternate text. Again, the purpose of including a description the of the actual harness, is missed.

“Pastel’s guide harness has a handle running the length of her back. The handle is attached with leather straps that go in front of the chest and behind the front legs.”

For more examples of how to convey the purpose and function of images with alternate text, see “Appropriate Use of Alternative Text” (http://webaim.org/techniques/alttext/) from WebAIM.

The same graphic can have different meanings depending on the context:

“Pastel at work”

“Pastel at work”
This is the same image and alt-text as above, but it is wrong here. It’s missing key information. The subtitle (‘Part 1…’) and the text is about leading, and the image reflects the text. Here it would be useful to describe the picture in with emphasis placed on the ‘leading’ activity.

“Pastel and her handler walking. Pastel is out in front and her back legs are level with her handler’s legs.”