Polygon sides should not cross one another. Here is Tim's frog, now done with a client-side map. Notice that unless you put the mouse cursor in certain regions you will see that the potential action is not defined. You can use any software which will return pixel coordinates to determine the coordinates to use for map regions. Make sure that the software measures from the upper left hand corner to the lower right hand corner.
Many programs measure from the lower left to the upper right.
If you load this file, you will see your image and when you move the mouse cursor around you will see the pixel coordinates down in the bar at the bottom of the browser. Not all browsers support client side clickable pictures. To deal with such browsers, you can use both the old server side syntax and the new client side syntax. Browsers ignore any tags which they do not understand, so an old browser would ignore the instructions for creating a client side map, but they would pay attention to the instructions for a server side map. If a browser supports client side clickable images, then the instructions for the client side maps take precedence over the server side maps except in regions where no action has been defined.