DES 4.2 Specify full descriptions for informational images
Complex images such as charts, diagrams and graphs need more description than simple alternative text alone (see DES 4.1) can reasonably display.
- Specify the inclusion of a longer description:
- On the same page, near the image (recommended);
- On a separate page, linked using:
- A normal text link to the description (recommended),
- Specify the developer uses longdesc to point to the url - screen readers can use this code to link to the description,
- A '
[d]' link placed after the image to point to the url (use a normal link though if possible - the use of [d] links is becoming less common and less well known).
- If providing a description on a separate page, the resulting linked page should contain all of the following:
- A clear title;
- An appropriate description of the complex image;
- A link back to the original page.
- The description should convey the essential informationThat you are trying to provide by including the image - don't over do it if unnecessary, for example for a graph:
- 'trend in ...':
- describe key aspects and trends if that is what is essential;
- Individual data points:
- place in a table or list if the individual data points are important.
- 'trend in ...':
Note - added bonus: long descriptions assist all potential users to extract the essential information - they help you explain your intention for including the image.
The descriptions will also be indexed by search engines making your information more discoverable.
