Accessibility Guide and Toolkit

When inserting images and graphical elements into your document, carefully consider the purpose of the image – what is it conveying? Does the object enhance the material? What information would be lost if the image was not available?

If the object conveys meaning, you need to describe the image for people who may be unable to see the image or for whom the image fails to load. If your image only requires a short description, you can describe the image in the alt text.  If your image requires a longer description, such as a diagram, include an image description in the surrounding text. If the object does not enhance the material but is still being provided to enhance visual appeal, set the image as hidden or decorative for screen readers. 

Alt text is a short image description of a visual element that can be accessed by a screen reader.  Screen readers announce when they encounter an image, so you do not need to include “image of” or “picture of” in your description.  Most alt text descriptions are limited to 100 characters. 

Alt text conveys the same information and meaning that the original image contains.  When you write your alt text, describe the information that would be lost without the image. The level of detail required depends on the purpose of the image; you need to describe all elements you want the reader to understand from the visual object. 

If the image is functional, such as the image of an arrow representing the next button, use the alt text to describe the function of the image.  In the case of the arrow for the next button, alt text could read "go to next page" because the image's purpose is more meaningful than its appearance. 

Learn more about writing effective alt text from WebAIM.

If an image or graph requires a description exceeding alt text limits, set the alt text as a description of the image's purpose and then use the accompanying text to describe the information contained in the image. 

Images requiring longer descriptions tend to be complex diagrams or infographics conveying important or complicated information. For these situations, set the alt text to the title of a figure and use the surrounding text to explain the information contained in the figure. The image should enhance the presentation of information but not be the sole source of information.  

If your image does not convey meaning but you still want to include it for design purposes, you can mark the image as decorative. The checkbox to mark an image as decorative is usually available from the edit alt text menu. 

When placing a graphical element into your document, do not interrupt text flow. When images are allowed to float or text is allowed to wrap, images can interrupt text flow by suddenly appearing in the middle of a sentence or paragraph and disrupting reading comprehension. 

For Microsoft Word, insert images in line with text so they are announced by screen readers in a logical sequence with the accompanying text.

For Microsoft PowerPoint, use available slide layouts with image placeholders to insert images.  Slide layouts available from Microsoft already include a tagged reading order structure for screen readers. To preserve the reading order structure, do not insert additional content into existing slide layouts. Instead, add a new slide for the information that does not fit on the previous slide. 

For PDFs, review and touch up the tagged reading order to ensure images are encountered in an appropriate sequence with text.