A Novel Reversible Watermarking Method for Stereo-Pair Image Based on Ac-Pair Swapping

In recent years, with the rise of new media technologies such as artificial intelligence, blockchain, and virtual reality, research on digital watermarking and ownership protection in related fields has also begun to spread. As an important part of virtual reality, the protection of the copyright of stereo-pair images through digital watermarking has also begun to gain prominence. This paper presents a robust digital watermarking technique that can protect stereo-pair images and still decode meaningful watermark images after attacks. The core concept of the proposed hiding method is that, during the JPEG compression process, after completing DCT and quantization operations, a pair of AC values is chosen for each block, and based on their order of magnitude, it is decided whether the embedded information is 0 or 1. This method embeds only one bit per block and swapping of AC values if necessary. Although this approach results in a higher degree of image destruction while offering high robustness, the proposed method also provides an algorithm for restoring the original image. After leaving the public network, the watermark can be removed with a private key, eliminating the damage caused by the watermark to the image. Experimental results show that the proposed method has good robustness against attacks such as “JPEG recompression” and “affine transform distortion”, and the watermark can still be decoded and verified after such attacks. It also ensures that in most cases, the watermark can be completely removed, restoring the original image.