Self-embedding Fragile Watermarking Scheme Based on Bicubic Prediction

To improve the quality of recovered images, a selfembedding fragile watermarking scheme is proposed based on the bicubic prediction. To take into account the PFA and the watermark payload, the 6-bit recovery data of a 2×2 block and the 8-bit key-based data of a 4×4 block are generated and inserted in the other 2×2 block and 4×4 block based on secret key, respectively. The validity of a 2×2 image block is determined by combining the recovery data with the key-based data. To improve the recovery quality, the recovery method based on bicubic prediction is designed to reconstruct the invalid blocks whose recovery watermark embedded in the other block is also destroyed. Simulation results demonstrate that the proposed scheme allows image recovery with an acceptable visual quality (PSNR ≈ 25 dB) up to 75% tampering.