Module 3 | PowerPoint | Images Overview

Images

Images convey information quickly and powerfully—assuming they can been seen and understood. However, some readers may not understand the meaning of the image while others may not be able to see it due to visual impairment, personal viewing preferences (especially on the web), or technological limitations. Tagging images with alternative text ("alt text" or "alt tag") provides a textual alternative to visual information.

The alternative text serves several functions: 

  • It is read by screen readers in place of images allowing the content and function of the image to be accessible to those with visual or certain cognitive disabilities

  • It is displayed in place of the image in browsers if the image file is not loaded or when the user has chosen not to view images

  • It provides a semantic meaning and description to images which can be read by search engines or be used to later determine the content of the image from page context alone

Adding alternative text to photos is first and foremost a principle of web accessibility. Alt text is displayed in place of an image if an image file cannot be loaded or seen. Visually impaired users using screen readers will read an alt attribute to better understand an on-page image.

Context is Everything

When writing the appropriate alternative text for course images, context is everything. The alternative text for one image may be very different based upon the context and surroundings of the image itself. There are also "decorative" images, which do not require a descriptive alternative text but rather need to be noted as an image used for decorative purposes. Navigate to the following pages which provide examples of images in various contexts as well as the "how-to" of making your images accessible. 

Sources