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Adding ALT Text to Images

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

  1. Open the page in Edit mode and select the image. The toolbar will now display the "Picture Tools" tab.
    Step 1 - select and image and the Picture Tools tab appears
  2. Click the "Design" link under the "Picture Tools" tab title; the Image Properties options appear.
    Step 2 - click the Design tab and the Alt Text properties input appears
  3. Enter a brief description for the image (125 characters or less).
    Step 3 - enter a brief description
  4. 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:

Decorative images

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:
Decorative images should have an empty alt tag

When images serve as links, buttons, or complex "image maps," alt tags must describe the associated function, as in the following examples.

  1. Describing the destination of the link:
    Image link alt tag should describe destination
  2. Describing the function that will be performed upon clicking:
    Button alt text should describe function

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:
alt text where redundant

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:
Link to equivalent text should accompany chart and graph images

Slideshows

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.

Why this matters

"ALT tag" refers to the "alternative text" attribute of the IMG element that places an image on a web page. The ALT tag adds a text description to an image, indicating the content and purpose of the image.

Screen reader users will hear the contents of the ALT tag read to them, allowing them to understand what an image represents.

Images that are purely decorative (i.e., convey no information) need not have text content in the ALT attribute; in other words, the ALT tag can be empty, but it must still be present. (See example.)

If no ALT attribute is provided, a screen reader user will simply hear "Image," which is uninformative, frustrating, and unacceptable.

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