Forty years of research in character and document recognition---an industrial perspective
1. Introduction
Presented is an industrial view on the character and document recognition technology, based on some material presented at ICDAR [1]. Commercial optical character readers (OCRs) emerged in the 1950s, and since then, the character and document recognition tech-nology has advanced significantly providing products and systems to meet industrial and commercial needs throughout the develop-ment process. At the same time, the profits from businesses based on this technology have been invested in research and development of more advanced technology. We can observe here a virtuous cy-cle. New technologies have enabled new applications, and the new applications have supported the development of better technology. Character and document recognition has been a very successful area of pattern recognition.
The main business and industrial applications of character and document recognition in the last forty years have been in form read-ing, bank check reading and postal address reading. By supporting these applications, recognition capability has expanded in multiple dimensions: mode of writing, scripts, types of documents, and so on. The recognizable modes of writing are machine-printing, handprint-ing, and script handwriting. Recognizable scripts started with Arabic numerals and expanded to the Latin alphabets, Japanese Katakana syllabic characters, Kanji (Japanese version of Chinese) characters, Chinese characters, and Hangul characters. Work is now being done to make Indian and Arabic scripts readable. Many different kinds of paper forms can be read by todays OCRs, including bank checks, post cards, envelopes, book pages, and business cards. Typeface standards such as OCR-A and OCR-B fonts have contributed to making OCRs reliable enough even in the early stages. In the same context, spe-cially designed OCR forms have simplified the segmentation problem and made handprinted character OCRs readable even by immature recognition technology. Todays OCRs are successfully used to read any type of fonts and freely handwritten characters.
The field of character and document recognition has not always been peaceful. It has twice been disturbed by waves of new digital technologies that threatened to diminish the role of OCR technol-ogy. The first such wave was that of office automation in the early 1980s. Starting then, most of information seemed to be going to be born digital, potentially diminishing demand for OCRs, and some researchers were pessimistic about the future. However, it turned out that the sales of OCRs in Japan, for example, peaked in the 1980s. This was ironically due to the promoted introduction of office com-puters. It is well known that the use of paper has kept increasing.
We are now facing the second wave. IT and Web technologies might have a different impact. Many kinds of applications can now be completed on the Web. Information can flow around the world in an instant. However, it is still not known whether the demand for char-acter and document recognition will decrease or whether new appli-cations requiring more advanced technology will be created. Search engines have become ubiquitous and are expanding their reach into the areas of image documents, photographs, and videos. People are re-evaluating the importance of handwriting and trying to integrate it into the digital world. It seems that paper is still not going to dis-appear. Mobile devices with micro cameras now have CPUs capable of real-time recognition. The future prospects of these developments are discussed here.
2. Brief historical view
2.1. Overview
The first practical OCR appeared in the United States in the 1950s, in the same decade as the first commercial computer UNIVAC. Since then, each decade has seen advances in OCR technology. In the early 1960s, IBM produced their first models of optical readers, the IBM 1418 (1960) and IBM 1428 (1962), which were, respectively, capable of reading printed numerals and handprinted numerals. One of the models of those days could read 200 printed document fonts and were used as input apparatus for IBM 1401 computers. Also in the 1960s, postal operations were automated using mechanical letter sorters with OCRs, which for the first time automatically read postal codes to determine destinations. The United States Postal Service first introduced address-reading OCRs, which in 1965 began reading the city/state/ZIP line of printed envelopes [2]. In Japan, Toshiba and NEC developed handprinted numeral OCRs for postal code recognition, and put them into use in 1968 [3]. In Germany, a postal code system was introduced for the first time in the world in 1961 [4]. However, the first postal code reading letter sorter in Europe was introduced in Italy in 1973, and the first letter sorter with an automatic address reader was introduced in Germany in 1978 [5].
Japan started to introduce commercial OCRs in the late 1960s. Hitachi produced their first OCR for printed alphanumerics in 1968 and the first handprinted numeral OCR for business use in 1972. NEC developed the first OCR that could read handprinted Katakana in ad-dition in 1976. The Japanese Ministry of International Trade and In-dustry (since renamed the Ministry of Economy, Trade and Industry) conducted a 10-year 20 billion-yen national project on pattern in-formation processing starting in 1971. Among other research topics, Toshiba worked on printed Kanji recognition, and Fujitsu worked on handwritten character recognition. The ETL character databases in-cluding Kanji characters were created as part of this project, which contributed to research and development of Kanji OCRs [6]. As a by-product, the project attracted many students and researchers into the pattern recognition area. In the United States, IBM introduced a deposit proc
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