Adding Descriptive ALT Text to Images
Any non-text element that conveys information required for comprehension of content or for navigation must include a text equivalent that communicates the same information as its associated element.
For images, this requirement can usually be satisfied by the alt attribute (a.k.a. "ALT tag") of the <img> html object. For more complex graphics, a more extensive description can be linked to or provided in the immediate context of the graphic.
ALT tags for simple images can be easily added using Sharepoint's GUI, as described in the next section.
See also specific guidelines for tagging images that are purely decorative, used as links, graphs and charts, and slideshows. (Media such as video, audio, and presentation "slides" are subject to similar requirements.)
Adding ALT Tags with Sharepoint's Toolbar
- Open the page in Edit mode and select the image. The toolbar will now display the "Picture Tools" tab.
- Click the "Design" link under the "Picture Tools" tab title; the Image Properties options appear.
- Enter a brief description for the image (125 characters or less).
- Save/Publish the page as usual.
Guidelines for Use of ALT Tags
While "images that convey information" must have an alt tag with descriptive text, other requirements may apply in specific circumstances:
Images that are purely ornamental (think, clip art) or inconsequential (spacer gifs), and even some photos that add no significant information to a page, should NOT have alt tags with descriptive text. Such images must have alt tags, but the tag's "value" should be empty (alt=""). Screen readers simply skip over images with empty alt tags.
Fortunately, when an image is added to a page using the Sharepoint GUI, an empty alt attribute is automatically created along with the IMG tag HTML. So if your image is purely decorative, with no real informational value, simply leave the Alt text blank:
When images serve as links, buttons, or complex "image maps," alt tags must describe the associated function, as in the following examples.
- Describing the destination of the link:
- Describing the function that will be performed upon clicking:
Except . . . when the function of the image link is evident from the context in which it appears, its alt tag should be empty to avoid unnecessary redundancy:
Images of Charts, Graphs
When an image of a graph or chart conveys complex information, it is best to provide equivalent text, either immediately adjacent to the image, or as a link to a description in HTML or an accessible PDF:
ACPS Slideshows, as currently implemented, are fully accessible. However, because these are implemented using external html files, the "alt" text for constituent images are not editable directly in Sharepoint. Contact the ACPS Web Team for help.