The robust watermarking method embeds the information in the image to protect the copyright. The embedding process will destroy the original image and cannot be effectively applied to the images used in the medicine and military with high integrity demand. A robust zero-watermarking algorithm for lossless copyright protection of color images without changing the original image was proposed in this paper. A novel quaternion polar complex exponential transform (NoQPCET) was firstly constructed with effectively improved performance; then the NoQPCET and chaotic system based robust color image zero-watermarking algorithm was suggested for lossless copyright protection of color images. In the proposed algorithm, the robustness against geometric attacks was enhanced due to the excellent geometric invariance of NoQPCET, and the security was also improved because of the initial value sensitivity of the chaotic system. Experimental results showed that this algorithm had very strong robustness against both geometric attacks and common image processing attacks, and was superior to other algorithms.

鲁棒水印方法将信息嵌入图像中以保护版权。嵌入过程会破坏原始图像，无法有效应用于对完整性要求较高的医学和军事图像。提出了一种不改变原始图像的彩色图像无损版权保护的鲁棒零水印算法。首次构建了一种新的四元数极坐标复指数变换（NoQPCET），并有效提高了性能；然后提出了基于NoQPCET和混沌系统的鲁棒彩色图像零水印算法对彩色图像进行无损版权保护。在所提出的算法中，由于NoQPCET优异的几何不变性，增强了对几何攻击的鲁棒性，并且由于混沌系统的初值敏感性也提高了安全性。实验结果表明，该算法对几何攻击和常见的图像处理攻击都具有很强的鲁棒性，优于其他算法。