Active <area> elements must have alternate text
How to Fix the Problem
  Ensure each clickable <area> within an image map has an
  alt, aria-label or
  aria-labelledby attribute value that describes the purpose of the
  link.
  <img> elements with usemap attribute values
  identify image maps that use a set of <map> tags enclosing
  clickable hotspots defined by area attribute values. An
  additional alt attribute is required to define alternate text for
  each area:
<img src="images/solar_system.jpg" alt="Solar System" width="472" height="800" usemap="#Map"/>
<map name="Map">
    <area shape="rect" coords="115,158,276,192" href="http://en.wikipedia.org/wiki/Mercury_%28planet%29" alt="Mercury">
    <area shape="rect" coords="115,193,276,234" href="http://en.wikipedia.org/wiki/Venus" alt="Venus">
    <!-- Remaining hotspots in image map... -->
</map>Bad Example
Don't use server-side image maps that rely on mouse click coordinates. These maps are not keyboard accessible, and do not provide text alternatives to the actionable areas of the image map.
<a href="/maps/nav.map"><img src="/images/navbar.gif" ismap></a>Why it Matters
  Screen readers have no way of translating images into words. It is important
  that all images, including image maps, have alt text values.
Screen readers typically announce the filename of the image if alternative text is missing. Filenames do not adequately describe images and are not helpful to screen reader users.
Rule Description
An image map is a single image with many clickable areas. Like all images, an image map must have alternate text for each of the different clickable areas, as well as for the larger image itself, since screen readers have no way of translating graphics into text.
The Algorithm (in simple terms)
Ensures area elements of image maps have alternate text.
 
              

