WORD SPOTTING TECHNIQUES IN DOCUMENT ANALYSIS AND RETRIEVAL — A COMPREHENSIVE SURVEY

In this chapter, we present a comprehensive review of word spotting techniques and concepts. Word spotting has been adopted and used by various researchers as a complementary technique to Optical Character Recognition for document analysis and retrieval. The various applications of word spotting include document indexing, retrieval and information filtering. Word spotting techniques are based on matching the visual similarity between two images. Unlike OCR techniques, conversion of documents into machine readable codes and machine recognition is not required in word spotting techniques. Proper estimation of bounding boxes, selection and use of proper features as well as robust image matching methods are considered to be the most important aspects of a word spotting system. Here we include the important aspects of word spotting techniques, such as pre-processing, features, matching algorithms and evaluation methods.