DEV 6.2 - Provide full descriptions for informational images
Complex images such as charts, diagrams and graphs need more description than an alt
attribute alone can reasonably display.
- Add a longer description:
- on the same page, near the image (recommended);
- On a separate page, linked using:
- a normal text link to the description,
longdesc
to point to the URL,- A '
[d]
' link placed after the image to point to the URL (use a normal link 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 information that 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.
Longdesc code example
<img src="graph.gif" alt="graph of sales 2004/5" longdesc="graph.html">