Graphical symbol retrieval using a branch and bound algorithm

Graphical symbol spotting and retrieval in document images is an important sub-field in document analysis. This paper presents a branch and bound algorithm for spotting a queried graphical symbol in documents. The technique utilizes geometric primitives as feature points. The preprocessing of the input images involves applying some ordinary morphological operations and then sampling to get points or segments. As for the search; a branch and bound geometric matching algorithm is used to locate the required symbol(s) in the documents. The presented method has been tested on documents that contain electronic circuits and it achieved high accuracy.