Quantum Robust Coding for Quantum Image Watermarking

Spatial domain-based quantum image watermarking is an efficient quantum watermarking method due to easy implementation and low complexity. However, robustness is challenged because the embedded watermark information is prone to errors, especially noise interference and inversion attacks. In order to improve the robustness of quantum watermarking algorithms, this paper proposes a Quantum Robust Coding (QRC) for the watermark information transformation before embedding. The QRC changes the watermark qubit according to the carrier information indicator, which is associated with the brightness and darkness features of the watermark image. We present detailed coding methodology and give the quantum circuits. The quantum circuits for realizing “Salt and Pepper” noise are also provided. We encode 40 binary watermarks with QRC and embed them into grayscale images, then evaluate the Bit Error Rate (BER) under “Salt and Pepper” noise and inversion attacks. By comparing with the watermarking process without QRC, the BER of watermark using QRC is reduced by an average of 26.63%, with the highest being 27.86%. Experiments with inversion attacks on images demonstrate that our QRC has an information invariant property with a BER of 0. Finally, we compare with existing schemes by a quantum watermarking using QRC, and the results show that our scheme has stronger robustness advantage.