at random 任意,随便; 任意地,随机地; 随便地,任意地; 随机的,任意的; 随机地,任意地; 随意地,任意地; 随意地,随机地
random n. 〔罕用语〕胡乱行为,偶然的[随便的]行动[过程]。 adj. 1.任意的,胡乱的,随便的;(话等)信口乱说的;(人等)偶然碰到的。 2.随机的;【物理学】无规则的;(石工)(大小)不齐的。 a random guess 瞎猜。 a random shot 乱射(的子弹);流弹。 at random 碰运气地;无目标地,漫无目的地。 n. -icity 随机性,无规性。
Random group and random permutation of idea 的随机群和随机置换
Since watermark is added to visually more important regions of host image according to human visual system , and a pseudo - random permutation is performed in the wavelet domain before the watermark is embedded , which disperse the spatial relationship of pattern . therefore , even if the shape or the major location of the watermark is estimated , it ' s extremely difficult to detect or destroy the watermark with the cipher of permutation unknown 由于利用人眼视觉系统把数字水印嵌入到图像视觉较重要区域中,并且水印在嵌入前进行了小波域上的伪随机置乱,打乱了水印的空间关系,因此在置乱密钥未知的情况下,即使能估计出水印的形状和嵌入的主要位置,对水印的检测和破坏也是非常困难的。
The watermarking scheme based on wavelet decomposition and discrete cosine transform using a binary pattern or gray - level pattern as the watermark , the scheme initially performs wavelet decomposition of the host image and the watermark with different hierarchy . after the pseudo - random permutation , each decomposed layer of the watermark is embedded into the dct domain of corresponding decomposed layer of the host image 基于小波分解和余弦变换结合的水印方案算法以二值图标或灰度图标作为水印,将原图像和水印信号分别进行不同层次的小波分解,分解后的水印各分量伪随机置乱后分别嵌入到原图像相应分解层各分量的dct域中。