The singular values of each image sub-block is gained to form a vector by applying theSVD procedure. Then a watermark is embedded by modulating the vectors in terms of two secret keys.
首先将图像进行分块,然后通过各个图像子块的SVD变换获得奇异值,将各子块的奇异值组成向量后再采用双密钥调制方式嵌入水印。
参考来源 - 基于SVD的图像数字水印算法研究·2,447,543篇论文数据，部分数据来源于NoteExpress
When the compression ratio is high, there is uncontinuous on the image sub-block edges, such discontinuities effects on the performance of the block in the visual.
当压缩比较高时，图像子块边缘出现不连续的现象，这种不连续在视觉上表现为块效应。
Nevertheless, the smaller size of sub image also results to clearer block effect, and the fusion results achieved by ridgelet will also approximate to wavelet transform.
但是，分割尺寸越小，重构图像的块状效应越明显，而且分割越小图像所表示的方向也越少，效果也近似于小波变换。
Secondly, the use of fractal dimension as an index to divide the image to sub-block, can receive high similarity sub-blocks.
其次，采用分形维数为指标来划分图像的相似块，能够得到具有较高相似度的块。
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