步长选择 meaning in English
step length selection
Examples
- The results here improve and generalize those in the literature . in addition , a new step - size rule , which need not a line search , is presented for the damped gauss - newton algorithm . a nice global convergence result is obtained
同时，我们给出了一种不需要线性搜索的新的步长选择方法，研究了在此步长规则下的阻尼gauss - newton方法，得到了一个更好的全局收敛结果。 - In this paper , chroma dc coefficients are selected as the carrier data because chroma dc coefficients are robust . also , alterable steps are used to select one part of the coefficients , so the watermark is imperceptible ; before watermark embedding , the watermark is divided into many parts , every part is individually embedded into one gop of the video , even if a gop is destroyed , the watermark can be extracted correctly , this methods promotes the robustness of the watermark ; in addition , in order to promote the security of the watermark , the user ' s id and password are used to generate chaos sequence by the chaos system which is created in this paper , later , watermark is mixed by the chaos sequence . also , the embedding position of the watermark bit is modified by one chaos sequence , so , unauthorized person can not extract or remove the watermark , since the embedding position is unknown
本文认为，色度dc系数是鲁棒性非常好的参数，因而选择色度dc系数作为水印信息载体，同时，采用可变的步长选择部分系数，保证了水印的隐形性；在嵌入水印时，本文采用水印信息“网格划分” 、各子块独立嵌入视频的方案，由于水印信息子块是相对独立的嵌入视频中的每一相对独立的图组当中，即使某一图组收到一定破坏，也能够恢复水印信息，使水印的健壮性得到提高；此外，为了提高水印信息的安全性，在嵌入水印信息时，根据用户输入的id号和密码，利用本文构造的混沌系统产生的混沌序列对水印信息进行变换，同时，对每一水印信息比特的嵌入位置也采用了伪随机序列进行调整，这样，未授权用户不能提取水印信息，也难以擦除其中的水印信息，因为嵌入的位置是未知的。