Patent ID: 8675969

Claim:
A method for detecting page boundaries of a book document image, comprising: an edge image detecting step for detecting an edge image from the book document image; a horizontal page boundary detecting step for detecting top page boundaries and bottom page boundaries on the edge image, wherein the horizontal page boundary detecting step includes a straight line segment detecting step for detecting a plurality of straight line segments on the edge image, a straight line part selecting step for selecting straight line parts of the top page boundaries and the bottom page boundaries from the plurality of straight line segments based on the following criteria: a) on a top side, a straight line segment of a top page boundary of a left page and a straight line segment of a top page boundary of a right page are approximately on the same straight line, and on a bottom side, a straight line segment of a bottom page boundary of the left page and a straight line segment of a bottom page boundary of the right page are approximately on the same straight line, b) on the top side, in case more than one pairs of straight line segments satisfy criterion a), if a vertical distance between an upper pair of straight line segments and a lower pair of straight line segments is larger than a pre-determined threshold, the upper pair of straight line segments is chosen as the straight line parts of the top page boundaries; otherwise the lower pair of straight line segments is chosen as the straight line parts of the top page boundaries; on the bottom side, in case more than one pairs of straight line segments satisfy criterion a), if a vertical distance between an upper pair of straight line segments and a lower pair of straight line segments is larger than a pre-determined threshold, the lower pair of straight line segments is chosen as the straight line parts of the bottom page boundaries; otherwise the upper pair of straight line segments is chosen as the straight line parts of the bottom page boundaries, and a curvature part detecting step for detecting curvature parts of the top page boundaries and the bottom page boundaries on the edge image based on the straight line parts of the top page boundaries and the bottom page boundaries; a binding center line detecting step for detecting the binding center line by searching an intersection point of the left page and the right page on the top page boundaries and the bottom page boundaries; a page width determining step for determining the page width of the book document image; and a vertical page boundary determining step for determining the left page boundary and the right page boundary by using the top page boundaries, the bottom page boundaries, the binding center line and the page width.