Promoting watermark performance by using energy reallocation

In this paper, we propose a so called energy reallocation scheme to promote watermarking robustness while not at the expense of imperceptibility which is desired to be resolved in the research area. The watermark strength is reallocated in a complementary manner such as to enhance the watermarked image quality by 3 dB not at the expense of watermark robustness. The complementary watermarks are embedded at adjacency positions to take advantage from the locally correlated attacks, e.g. smoothing and sharpening. To derive the reference modification bound for each DCT component, an attacking simulation scheme based on the spatial domain, JND is employed. The experimental study shows our method can gain about 3 dB benefit in PSNR beyond the single watermark with double strength method. And, our method can even compete in the extracted watermark quality with the latter. These results also show that the neighboring arrangement for the complementary watermarks locating indeed provides enhancement in watermark extraction.