A cylindrical surface model to rectify the bound document image

We propose a novel approach on how to rectify the photo image of the bound document. The surface of the document is modeled by a cylindrical surface. By the geometry of camera image formation, the equations using the cue of directrixes to map the points on the surface in the 3D scene to the points on the image plane are achieved. Baselines of the horizontal text line are extracted as projections of directrixes to estimate the bending extent of the surface, and then the images are rectified. The proposed method needs no auxiliary device. Experimental results are presented to demonstrate the feasibility and the application of the method.