Improved watermark extraction for printed and scanned watermarked document

In this paper, we address a problem in the watermark extraction process from the printed and scanned watermarked document. Because the information e.g. text, images, diagrams, etc., printed on the watermarked ready-to-print paper can be considered as noises introduced to the watermarked document, the accuracy of watermark signal extracted from the watermarked document can be improved by removing such noises as much as possible before performing the watermark extraction process. From this fact, we thus propose a new procedure to improve the accuracy of the extracted watermark. Our proposed procedure is efficient and very practical to implement with the existing watermarking scheme. The experimental results show improvements obtained from our proposed procedure.