Former books digital processing: image warping

In the present paper we will discuss the way to correct the text image warping due to old bookbindings which can not open to 180/spl deg/. Two methods have been experimented to measure the surface distortion of the paper The first method uses a diffracted laser beam and is operational for 1D distortion measurements. As former bookbindings may also present 2D distortion, we have developed a second method which uses a light projected network and which gives encouraging results.