Color Image of Tamper Detection and Recovery using Block-based Watermarking

in this paper, we propose a digital watermarking scheme about color image of tamper detection and recovery using block-based watermarking. Firstly, in our watermark embedding, each color channel (R, G, and B) is divided into 2x2 non-overlapping blocks. The embedding space is created by setting the three LSBs (least significant bits) of selected each block to zero, which will hold the authentication and recovery codes. The authentication codes are obtained through doing exclusive-or (XOR) both the extracted local features of image blocks and the generated global features of the original color image. The recovery codes are generated using block-mapping original color image and using color model conversion. Secondly, in the tamper detection, instead of examining each embedded authentication data, we get the global features of the tampered watermarked image through doing XOR both all the extracted authentication codes and the generated local features of tampered watermarked image blocks. And then we utilize a majority-selecting technique to detect the legitimacy of image blocks. Lastly, in the tamper recovery, we propose 3 stages to accomplish recovery ability. Experiment demonstrates that our scheme is oblivious, correctly localizes the tampering wherever the tampered positions are and can be successfully accomplish to recover with acceptable visual quality.