When you click on such a picture your client will generate a request to the server with the pixel coordinates appended to the URL specified. For example:
http://www.ifm.liu.se/foobar.map?123,454To handle this you create the text file "foobar.map" with a content something like this:
# sample.map circle (100,100) 50 http://www.ifm.liu.se/ rectangle (10,10) (100,100) ftp://ftp.lysator.liu.se/ polygon (0,0) (10,0) (10,10) /phttpd/ default http://www.lysator.liu.se/And then point to the image file and this .map file in your HTML document, by writing something like this:
This is a clickable image: <P> <A HREF="sample.map"> <IMG SRC="fine-picture.gif" ISMAP> </A>