With the continuous development of the computer network information technique, the problem of copyright protection of color images is increasingly getting prominent. Based on above issue, this paper presents a quaternary watermarking of color image using Schur decomposition. The superiorities of the presented scheme contains three points: Firstly, the algorithm obtains the maximum eigenvalue of the pixel block using Schur decomposition that have a high efficiency, and accomplishes the hiding and blind detection of color watermark by quantifying the maximum eigenvalue to four intervals. Secondly, the algorithm uses affine transform that have high security to encrypt the location of the color watermark pixels, which improves the security of the watermarking algorithm. Thirdly, the new idea of four intervals quantization is proposed to apply to this scheme. Simulation consequences indicate that the presented scheme can satisfy the needs of visual imperceptibility, and also has large watermark capacity, strong robustness and high security.

中文翻译：

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一种基于四进制编码的频域彩色水印方案

随着计算机网络信息技术的不断发展，彩色图像的版权保护问题日益突出。基于上述问题，本文提出了一种基于Schur分解的彩色图像四级水印方法。该方案的优点在于三点：首先，该算法利用效率高的Schur分解得到像素块的最大特征值，并通过将最大特征值量化为四个区间来完成彩色水印的隐藏和盲检测。其次，算法采用安全性高的仿射变换对彩色水印像素的位置进行加密，提高了水印算法的安全性。第三，提出了四间隔量化的新思想以应用于该方案。仿真结果表明，所提出的方案能够满足视觉不可感知的需求，并且水印容量大、鲁棒性强、安全性高。