Tomio Amano

A feature calibration method for watermarking of document images

This paper describes a feature calibration scheme for use in embedding and detecting watermarks in document images. Such watermarks have a variety of uses, including copyright protection, content identification, and tamper-proofing. In general, a watermark is encoded as a displacement of certain features that can be extracted from target document images. One of the technical challenges is reliable detection of the displacement when images are distorted by print-and-scan processes. We propose a calibration method that uses the difference between a two features extracted from two sets of partitions arranged symmetrically. Since this method counter-balances the cumulative effects on the features of distortions added in the print-and-scan process, the displacement can be reliably detected. The feasibility of the method was investigated by using the average width of character strokes is used as a feature.

A spelling correction method and its application to an OCR system

Abstract This paper describes a method of spelling correction consisting of two steps: selection of candidate words, and approximate string matching between the input word and each candidate word. Each word is classified and multi-indexed according to combinations of a constant number of characters in the word. Candidate words are selected fast and accurately, regardless of error types, as long as the number of errors is below a threshold. We applied this method to the post-processing of a printed alphanumeric OCR on a personal computer, thus making our OCR more reliable and user-friendly.

DRS: a workstation-based document recognition system for text entry

Document recognition system (DRS), a workstation-based prototype document analysis system that uses optical character recognition (OCR), is described. The system provides functions for image capture, block segmentation, page structure analysis, and character recognition with contextual postprocessing, as well as a user interface for error correction. All the functions except image capture and character recognition have been implemented by means of software for the Japanese edition of OS/2.<<ETX>>

A document recognition system and its applications

This paper describes a document entry system called the Document Recognition System (DRS), which facilitates the conversion of printed documents into electronic form. DRS was developed on a personal computer (PC) with an adapter card for recognizing more than 3000 Kanji characters. It provides a flexible framework for object-oriented management of data and processing modules. The framework allows the user to change the combination of processing modules and to select pipelining (parallel processing) or sequential processing. DRS includes processing modules for layout analysis functions such as blob detection, block segmentation, and model matching, and for character recognition functions such as Kanji character recognition, Japanese postprocessing, postprocessing by a user, and error correction through a user interface. The character recognition functions on the card and the other processing-related recognition functions on the PC work cooperatively in the proposed framework. Within the basic framework, we have customized DRS for practical applications. Examples of successful applications-entry into a text database, creation of an electronic catalog, entry of family registration data, and entry of tag data in a manufacturing process-provide evidence of the processing accuracy and robustness of the framework.

Character string detection algorithm using horizontal boundaries, and its application to a part number entry system

This paper proposes a new algorithm for detecting character strings in an image containing illustrations and characters. It also describes a part number entry system that utilizes this algorithm. The algorithm detects character strings by investigating the horizontal boundaries of rectangles representing characters strings. It can be performed a high speed, and can detect characters touching an illustration. Using this algorithm, the part number entry system extracts areas of part numbers scattered among illustrations and then recognizes the. This is a software program implemented on a personal computer, and is composed of four subprograms: detection of character strings, character recognition, post-processing, and flexible user-interface for error correction.

A Document Image Analysis and Recognition System for Japanese Family Registration

A family registration data entry system with functions for automatic form layout analysis and character recognition was developed. The layout analysis module first detects characters and ruled lines by using information on the top and bottom boundaries of smeared black components. It then determines the layout and identifies each field in the layout by comparing predefined models with detected lines. Character strings in the fields are recognized and matched with a dictionary to check whether a sequence is plausible as a Japanese word or not. The text data are registered in a database after they have been examined by an operator and keywords have been extracted. This system was actually used for the initial entry of typed family registration forms in Tokyos Toshima Ward, which contributed to establish the first computerized family registration system in Japan.