One. of the problems in camera-based document capturing
methods is to detect a paper of a document. which we focus
on in this paper. The captured images from digital cameras
have perspective distortions in most cases [2]. This should
be removed in capturing a document with an image. If the
boundary of a paper is extracted robustly, a homography to
_ remove perspective distortion could be estimated simply. A
’ homography ( H ). a 3 by 3 matrix in (l)‘ which maps points or
lines on a plane in the World to an image. could be determined.
’ h when we have four corresponding known points in the image
and the world [2].