The increased capacity of document image retrieval systems has necessitated an efficient method for indexing parts of document images. This is particularly important for graphs, because graphs provide the relationships between two items a user is searching for. This paper proposes a method that recognizes and indexes different kinds of graphs. Coordinates extracted from a graph are used to assign the graph to a category and to extract the labels attached to coordinates. The category is registered as an index of the graph. The extracted label images are recognized, converted into ASCII data, and also stored as indexes. We propose an automaton type recognition method that is based on a knowledge of graph formats. It, by detecting the coordinates and labels from among candidates, recognizes the graph type. The transitions of the automaton are driven by local features of the images. We also propose a system that retrieves parts of document images, and the automatic indexing method is also applied to this system.
['Masashi Koga', 'Tatsuya Murakami', 'Yoshihiro Shima', 'Hiromichi Fujisawa']
An Extraction Method of Search Indexes for Graph Image Retrieval