Abstract: Aiming at the poor geometric attack resistance of most current stereo image zero watermarking schemes, a
blind detection stereo image zero watermarking algorithm based on discrete octonion cosine transform (DOCT) and
speeded up robust features (SURF) was proposed. Firstly, the stationary wavelet transform (SWT) was performed on six
components of left and right views of the original stereo image under CIEXYZ color space. Secondly, the above six
low-frequency subbands were divided into non-overlapping blocks to construct the octonion image blocks at the
corresponding positions, and then the DC coefficients of all image blocks after DOCT were directly calculated in spatial
domain. Finally, the robust feature matrix was constructed by comparing the magnitude relationship between the
modulus of each octonion DC coefficient and their overall mean value. Then, the final zero watermark for authenticating
was generated by executing XOR operation on the feature matrix and encrypted watermark that had been processed by
quantum key scrambling and 2D-LALM system encrypting. In addition, the SURF method was employed to perform
geometric correction on the stereo image to be authenticated before the zero-watermark detection. Experimental results
show that the proposed algorithm displays better robustness against conventional attacks and geometric attacks.

Key words: stereo image, zero watermarking, discrete octonion cosine transform, speeded up robust features, geometric attack