Method of rearranging watermarked pixels for printed and scanned watermarked documents
ABSTRACT In this paper, we consider the problem of extracting the embedded watermark from the printed and scanned watermarked images. Since in a practical situation, the parameters settings in the printing and scanning processes between users are different, recovering the embedded watermark from the watermarked paper, after being scanned back to the computer, is difficult and contains high amount of errors. We hence propose a method of rearranging the printed and scanned watermarked pixels to implement with the pixel-wise based digital watermarking in order to improve the accuracy of the extracted watermark. The proposed method is simple, low complex, and possible for practical watermarking applications. With our proposed method, the watermarked paper can now be scanned back in various resolutions with small inclined angles. The experimental results show the improved performance in term of NC obtained from our method, compared to the lower accuracy from the previous method.