Look into the HTML MAP and AREA tags.
You create a <map> that is related to a given <img> and then within the <map> you have <area>s defined. Normally, you give an href= to each <area>, similar to an <a> tag, but you can defined onmouseover and onmouseout handlers for each <area>, as well.
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.