JND‐aware robust image watermarking with tri‐directional inter‐block correlation
Yunming Zhang, Zhenhua Wang, Yantong Zhan, Lili Meng, Jiande Sun, Wenbo Wan
Abstract
A novel block-level perceptual image watermarking framework is proposed in this study, including tri-directional correlation and a block-level just noticeable difference (JND) model. Specifically, the difference in the discrete cosine transform (DCT) coefficients of two blocks is calculated based on three directions in the neighborhood, called the tri-directional correlation (TriDC). Additionally, the representative alternating current (AC) coefficients along horizontal, vertical, and diagonal directions, which can describe structural patterns, are projected and merged for TriDC differences. Then, the difference of the DCT coefficient is modulated to a predefined zone depending on the JND-based offset. Finally, the extent of the watermarked AC coefficients is determined with perceptual JND adjustment. The experimental results demonstrate that the proposed scheme can protect most common image processing attacks; and has better robustness compared with recent zone modulation watermarking schemes and traditional watermarking methods.