SAIF: Creating Accessible Documents
Alternative text for images
Providing an alternative text for an image is helpful for people using assistive technology. For example, a screen reader will read out the alt text to the user. This is especially important if the image is conveying information not included in the text.
When a document is changed into another format, for example a PDF file, or incorporated into a webpage, the alt text will also be transferred and ensure better accessibility.
The text should be an alternative to the image.
Images with text
With any images that consist of text, the alt text shoudl be just the text as it is or if it is an acronym or abbreviation, spelled out. For example, this can be a logo or a brand name.
Photos and illustrations
For photos and illustrations, be imaginative and try to write what the photo is trying to convey. Write "a boy is eating a large hamburger dripping in sauce" if the image displays that. Writign suitable alt attributes for photographs can be tricky, but be imaginative.
Graphs and charts
Images as graphs and charts display information. Try to summarise any trends and developments in the alt text. For example, "the sales rates rose from 5% in January to 7% in March".
Decorative and spacing images
Images that are purely for the visual layout of a document shoudl not be read by assistive technology. Therefore these alt texts should be left with a null attibute '', so that a text screenreader will ignore the image.
Applying alt text
Right click on the image or graphic, select format picture and click on the alt text tab. In the alt text box, type in your description of the image.