I. INTRODUCTION Recently, documents i electronic form have been more and more popular, because the could be created, transferred, stored, and managed easily and efficiently. However, a lot of paper-based documents are still existing and used in daily life. They are not expected to disappear in the near future. Paper- based documents could be also captured and converted into digital format or electronic form with imaging sensors. There are two ways of capturing images of documents. One is to use traditional flatbed scanners, and the other is to utilize digital cameras.