Structure analysis method of graph image for document image retrieval

An automatic registration method for graph images which recognizes the structure of graphs is proposed. This method has the advantage of saving cost and time compared with the manual registration of types and labels of graphs as search indexes in electronic filing systems. The method is implemented in an advanced document image retrieval system, and the efficiency of the index registration is ascertained by experiment. The outline of this method is as follows: The types of graphs, the axes, and the labels of axes are initially detected. The types of graphs are classified into several categories and labels are attached to the axes. Next, the types are registered as indexes of the graphs, and the label images are recognized and converted into ASCII data, and also stored as indexes. An automaton model is used in the process of attaching the labels to analyze the components of the images. The automaton model refers to a knowledge-base of stored rules of layout structure. It then chooses appropriate labels for each axis.