Digital bleaching and content extraction for the digital archive of rare books

This paper reports our experience with the digitization project, "Digital Archive of Toyo Bunko Rare Books." The mission of this project is to make rare books accessible to the public through our Web site. This paper describes the image analysis aspect of this project from the viewpoint of digitization workflow, starting from image capture to Web site architecture. The uniqueness of this paper is in two-fold, digital bleaching and content extraction. Digital bleaching is a kind of image enhancement method with the aim of improving the readability of text for both humans and machines. Then textual content and graphical content is extracted automatically from the image, and applied indexing methods for searching. Our digital archive contains 53 books and about 14,000 pages, all of which are accessible on the Web site http://dsr.nii.ac.jp/toyobunko/