Much of the current popularity of the Web is related to the ease of use imparted by this functionality. This degraded performance is the major reason for the lack of realtime interactive feedback for users, mentioned above. Client-side image mapping is not a new concept. Hot-spot decoding may be performed locally because the polygon information is downloaded as part of the hypertext document. The polygon map and the associated image in this case are kept as two separate files.
Large document means increase in both transfer and parsing time.
This resulted in an extremely efficient method for encapsulating URL information with image data, and for enabling realtime hotspot decoding. A disadvantage of this implementation, however, was that use of the resulting file format is constrained by the MetaMAP patent. The Polymap work described in this paper was an attempt to allow advantages similar to those provided by the MetaMAP -based file format, while allowing free use of the Polymap file format without concerns about patent issues relating to object encoding. The Solution Our solution to the above problems is to include the polygon map data in the image. We utilize the application-specific field of the GIF 89 format to carry a compressed polygon map.