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
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。
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.
然后再选择另一对初始值和参数生成混沌序列，并以该混沌序列的主遍历矩阵对每图像子块进行置乱加密。
Then every block is scrambled with a new chaos sequences generated from the other pair of initial value and parameter.
通过理论推导及事例分析证得含平直单边缘图像子块，其DCT变换系数能量并不总是集中分布在与其空间边缘走向垂直的方向上。
It is proved that for a image subblock with a single straight edge, the DCT coefficient. energy compaction orientation and the spatial edge orientation are not always orthogonal.
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