A web interface to image-based concurrent markup using image maps

Image-based electronic editions (IBEEs) encode manuscripts using markup based on digitized images of the manuscript page. Due to the complex nature of editorial annotations, the resulting markup rarely forms a hierarchical structure - that is, ranges often overlap. To support web-based access to these editions, it is desirable to synchronize the display of markup and related satellite data with the corresponding portions of the image. This goal can be supported by image maps, which associate regions of an image with hyperlinks and actions. These links allow the user to view and manage editorial information and multimedia content associated with the markup. In this paper we present an efficient algorithm for constructing a mapping from overlapping or intersecting markup to regions of an image. This mapping satisfies four properties: (1) Regions are located near the corresponding text. (2) Regions corresponding to nested markup elements are themselves nested. (3) Regions corresponding to intersecting markup elements themselves intersect. (4) If region R contains a collection C of other regions, then R is strictly larger than the union of the regions in C. The fourth property above ensures spatial separation of the regions corresponding to nested markup. An image map satisfying these properties provides a convenient and intuitive linking between image coordinates and the corresponding markup ranges.