A method of local contrast mapping that changes the dynamic range of an original image to more closely match the dynamic range of the medium used for the reproduction. In accordance with an embodiment of the invention, a heuristic function is used to obtain a ranking of nodes in the DDG after setting delays at all identified by-pass pairs of nodes in the DDG to 0. The filter member has a closed top at one end and a retaining band at an opposite end that includes a connection base that is configured to attach with the housing connection flange. The other keywords from the identified first level categories are retrieved and the documents database is searched for documents having a user search term or a retrieved keyword. According to the present invention, the protrusion may protrude from the top plate.