基于CS-SCHT域的相幅结合水印算法

针对目前一些水印算法鲁棒性有待提高的问题，提出一种将相位和幅度相结合的CS-SCHT 域水印算法.由于相位的抗干扰能力比幅度的强，而幅度对旋转、剪切和缩放具有不变性，故若先将水印均分，然后再分别嵌入到同一系数的相位和幅度中，将可兼得相位算法和幅度算法的优势，进而达到提高鲁棒性的目的.仿真结果表明:新算法在未受到攻击时峰值信噪比达到 47.4517dB，在经过各种攻击后归一化相关系数也都在 0.9 以上.新算法的不可感知性好，并且对增亮攻击、旋转攻击、剪切攻击、高斯噪声攻击、高斯低通滤波攻击，以及JPEG压缩攻击都有很强的鲁棒性.

Robust Watermarking Algorithm Based on Combination of Phase and Amplitude of CS-SCHT Domain

In order to improve the robustness of watermarking algorithms， a watermarking algorithm based on the phase and amplitude of CS-SCHT coefficient was proposed. Since the anti-interference ability of the phase is stronger than that of the amplitude， and the amplitude is invariant to rotation， shear， and scaling， a watermark was divided equally and then embedded in the phase and amplitude of the same transformation coefficient， respectively， which can combine the advantages of phase algorithms and amplitude algorithms and achieve the purpose of improving the robustness. Simulation results showed that the PSNR of the proposed algorithm is 47.4517dB without attack， and the normalized correlation coefficients are above 0.9 with various attacks. The proposed algorithm is more invisible. Moreover， it is robust to brightening， rotation， cutting， noise attack， and low-pass filter attack of Gaussian and JPEG compression.