Image indexing applied to typewriter font identification

A method is described to extract an index from a binary character image for database storage and retrieval. The index is hierarchical in nature, and different parts can retrieve character image clusters of different sizes. A hierarchy of Kohonen neural networks is used to generate the clusters on which the indexing method is based. The application is the identification of the font from a sample of printed characters. This is particularly important for forensic document examiners who may have to match a document of unknown origin with the equipment that may have produced it. A computerised system is expected to considerably reduce the time required for each document search.