Images and graphics can be great additions to your web pages, and especially useful if they provide a basis for informing or directing visitors within your site. The challenge when using images is to make them as search engine friendly as possible. One of their uses that can cause issues within search engines is image mapping. An Image Map exists when one image has two or more links assigned to it.
Have you ever come across an image of a US map whereby each state has a different link pointing to a page dedicated to that state? On one hand, this image can be cut up into smaller, separate images that have one link each, but on the other hand, it can be one large image that has many links coded into it. It is the large map with multiple links coded into it (image map) that can cause problems for the search engines.
An Image Map is made up of complex code and it is this code that confuses search engines when they attempt to spider your web site. As was mentioned earlier, the same image can be made up of many smaller images, which removes the complex code, however, if it is used for navigation purposes, search engines still cannot index images or text on an image, as they are designed to look for HTML text and not read images.
If you would prefer to keep the Image Map on your site, the easiest and most effective search engine optimization technique, is to create a site map using standard HTML hyperlinks to link to every page on your site. After doing this, add a standard HTML link on each page of your site that links back to the site map. This will allow the search engines’ spiders to go through your entire site with ease and lead to better chances of search engine indexing and higher rankings!