DWT-DCT结合SURF与PSO的优化鲁棒水印算法
Robust Watermarking Algorithm That Combines DWT and DCT Integrated with SURF and PSO
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摘要: 针对优化水印算法中未最大化水印鲁棒性以及抗几何攻击较差的问题,本文提出了一种结合离散小波变换(Discrete Wavelet Transform, DWT)和离散余弦变换(Discrete Cosine Transform,DCT),并融合加速鲁棒特征(Speeded-Up Robust Features,SURF)与粒子群优化(Particle Swarm Optimization,PSO)的鲁棒水印算法。首先对宿主图像进行DWT以获得其低频图像,接着对低频图像进行分块DCT操作,最后每个DCT块选取两个系数嵌入一位水印。其中,嵌入位置与嵌入强度由PSO优化算法结合多种组合攻击选取。为了避免几何校正中使用原图像,本文利用SURF算法检测嵌入水印后图像的特征信息,并将其用于几何校正。实验表明,本文算法在峰值信噪比达到40 dB以上的情况下,在面临常规信号攻击和几何攻击时均有较好的鲁棒性。Abstract: To overcome the suboptimal robustness of watermarking algorithms and their weak resistance to geometric attacks, this paper proposes a robust watermarking algorithm that combines the discrete wavelet transform (DWT) and discrete cosine transform (DCT), and integrates speeded-up robust features (SURF) and particle swarm optimization (PSO). First, a host image was subjected to DWT to obtain its low-frequency image. The block-wise DCT was then used on the low-frequency image, with each DCT block embedding one watermark bit using two coefficients. The embedding positions and strengths were selected using PSO in combination with various composite attacks. To avoid using the original image in the geometric correction, the SURF algorithm was used to detect the feature information of the image embedded with a watermark and applied it to geometric correction. Experimental results demonstrated that the proposed algorithm achieved satisfactory robustness in the presence of common signal attacks and geometric attacks when the peak signal-to-noise ratio exceeded 40 dB.