1. A method for comparing documents, the method comprising: associating, by a processor, a respective weight with each of a plurality of information types including text-based information, graphical information, audio information, or video information; identifying for each of the documents, by the processor, one or more segments each corresponding to one of the plurality of information types; and estimating, by the processor, a similarity value between a first document of the documents and a second document of the documents by comparing each segment of the first document with a segment of the second document that corresponds to a same information type and combining results of the comparison based on the respective associated weights.