Sounds like an HTML image map. The map coordinates would be determined by the shape. Let's take a picture 100 pixels by 100 pixels. If I wanted the picture to be split into four smaller squares, each linking to a different place, the code might look something like this:
<img src="mypic.gif" usemap="menu_map" />
<map name="menu_map">
<area shape="rect" coords="1,1,50,50" />
<area shape="rect" coords="51,1,100,50" />
<area shape="rect" coords="1,51,50,100" />
<area shape="rect" coords="51,51,100,100" />
</map>
The coordinates are the pixel coordinates, based on the entire size of the image. In this case, the map areas are rectangular, so I give the coordinates of the top left and bottom right corners of each map area.
Hope this helps.
