Invertible fragile watermarking using fractal code and block-chain

This paper proposes a new watermarking scheme for image tamper detection and recovery, in which the tampered region can be detected and recovered in a fully automated fashion. To resist the vector quantization (VQ) attack and collage attack, all blocks in the original image randomly form a linear chain based on the secret key which is called block-chain. To achieve high-quality recovered image, we perform fractal coding for the original image, then insert the fractal image codes and watermark of an image block into the next block in the block-chain to obtain the watermarked image. By watermark extraction and detection procedure, the proposed scheme can determine whether the watermarked image has been altered and localize the tampered region, and then apply fractal decoding for image recovery. Abundant experimental results are given to show the effectiveness of the proposed scheme.