The following image is associated to an image map containing only one area, which corresponds exactly to the red square in the center. All red pixels should link to www.google.com.
The image is 30x30 pixels. The red square is 10x10 pixels, from (10, 10) to (19, 19), both included. Thus the map-area coords are "10,10,20,20" ((10, 10) = top-leftmost pixel includes, (20, 20) = top-leftmost pixel excluded from the area).
