Bitonal image creation for automatic content conversion

In this paper we address the problem of binarization of scanned documents which is a preprocessing requirement for most algorithms aimed at document image analysis. Two new approaches which focus on problem areas like low contrast documents, noise, and backside image showing through the paper sheet are presented in the following. First of all we propose a technique which is based on an initial preprocessing step followed by a conversion from the continuous space to the bitonal document. The first stage of this process focuses on document characteristics enhancement through contrast stretching for each color channel. The second step is a locally adaptive binarization process using color thresholding based on a Gaussian blur effect. Apart from that we present a noise-removal conversion technique based on combining the result of a series of threshold masks. Experimental results are given in order to verify the effectiveness of the proposed technique.