Patent ID: 7047238

Claim:
A document retrieval method for use in a retrieval system where a document database in which either prepared text data or text data extracted from image documents by a character recognition process is registered is searched to retrieve documents similar in content to a document specified by a retriever, the method comprising: a partial character string extraction step for extracting one or more partial character strings from said document specified by said retriever; a retrieval character string correction step for performing a character string correction process on said partial character strings obtained in said partial character string extraction step in order to correct recognition errors; a recognition error tolerance/retrieval step for retrieving documents, including candidate transcriptions that may arise due to recognition error, in accordance with retrieval character strings derived from said retrieval character string correction step; and a similarity calculation step for calculating the degree of similarity to the document specified by the retriever using the frequency-of-occurrence information about retrieval character strings in the documents that are extracted from said database in said recognition error tolerance/retrieval step.