Digital Watermarking Algorithm for QR Code Images Based on DCT and Blocked Images

摘要

To the problem that digital watermarking algorithm cannot resist cropping attack effectively, we propose a cropping resistance blind watermarking algorithm based on DCT in this paper. We use the QR code, which is coded from the text or image information, to be the watermark. First of all, carrier image is partitioned into m × n blocks and the QR code is compressed. Then, processing each block of carrier image with block DCT based method. The watermark information and keys are embedded in the corresponding intermediate frequency coefficients. In the end, repeating the last step m × n times in order to finish the watermark embedding. The experimental results illustrate that this algorithm can resist more than 90% of the cropping attacks and for all the cases considered in this paper is more robustly to attacks.