An improved new method for watermarking technology based on discrete cosine transform technology is proposed in concern of its poor robustness. The new method takes use of the average value of high frequency band coefficients in discrete cosine transform approaching zero as its characteristic, combined digital watermarking with disorder permutation method as the preprocessing. The result testifies improved discrete cosine transform can not only retrieve the digital watermark with better performance, and the image from which the watermark is retrieved nearly in perfect condition, shows better robustness.%针对离散余弦变换存在健壮性不理想的缺陷,提出一种改进的基于离散余弦变换的数字水印新方法.该方法在利用离散余弦变换中高频带系数平均值接近零的特性基础上,将数字水印加上乱序排列法的前置处理.实验结果证明:改进的离散余弦变换不仅能较好地取回数字水印,而且取出数字水印后的图像接近完美,健壮性较好.
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