基于DWT域对数量化索引调制的数字水印算法

摘要

为了提高水印的透明性和鲁棒性,解决QIM均匀量化不适用于非均匀信号的问题.引入μ律技术,将小波分解与对数量化索引调制结合,提出基于DWT域的对数量化索引调制数字水印算法.算法对原始图像进行离散小波变换,对变换后的近似部分系数运用μ律函数,再用QIM方法嵌入二值水印.选择合适的嵌入位置,通过对量化步长和参数进行讨论得到其最优值.仿真实验结果表明,该算法与以前的量化算法相比提高了水印的透明性,并对高斯噪声、中值滤波、JPEG压缩等常见攻击具有更强的鲁棒性.%To increase the invisibility and robustness, a digital watermarking algorithm based on DWT domain is combined with μ-law technology and logarithmic quantization index modulation.The algorithm has solved the problem of not being applicable to non-uniform signal for QIM uniform quantization.The original image is conducted with discrete wavelet transform.Then the μ-law function is applied to the approximate part coefficients of the original image.The transformed signal is quantized to embed binary watermark data by using QIM.The watermark embedding position, quantization step and parameters are discussed to obtain optimum values in this paper.Experimental results show that this algorithm improves invisibility of the watermark.Moreover, the proposed scheme has strong robustness against common attacks, such as Gaussian noise, median filtering, JPEG compression.