基于视觉显著模型的音视频交叉水印算法

提出一种基于Itti视觉显著模型的音视频交叉水印算法.首先利用音频码流的低通幅值特性生成水印,并嵌入到视频码流中;其次解码视频码流的关键帧Ⅰ帧,获取YUV序列上的亮度(Y)分量,并对其进行显著性分析;最后分块对非显著区域进行DCT变换,并通过量化索引调制嵌入水印.实验结果表明,该算法将嵌入水印后的关键帧平均PSRN值提高了1.678 5 dB,缓解了水印不可见性和鲁棒性的矛盾,实现了音视频码流之间的交叉保护.     

综合物探在寻找斑岩型钼多金属矿床中的应用

以豫南大别山北麓地区汤家坪大型斑岩型钼多金属矿床为例,阐明了豫南大别山北麓地区斑岩型钼多金属矿床的成因以及其地质与地球物理特征。通过在汤家坪钼多金属矿区开展综合物探找矿（可控源音频大地电磁测深法和频谱激电法）、剖面性试验研究和对区内所出露的岩（矿）石标本进行物性测试,试验及测试结果表明,该地区斑岩型钼矿床具有高阻高极化的物性特征,可控源音频大地电磁测深法和频谱激电法对成矿地质体（花岗斑岩体）有较为明显的显示。经钻孔验证表明,可控源音频大地电磁测深法和频谱激电法在该地区寻找斑岩型钼矿床是行之有效的,为今后在该区域寻找斑岩型矿床提供了技术参考,也为下一步推进该区地质找矿工作统筹部署和快速突破提供技术保障。     

An oblivious fragile watermarking scheme for images utilizing edge transitions in BTC bitmaps

As one of the famous block-based image coding schemes,block truncation coding(BTC) has been also applied in digital watermarking.Previous BTC-based watermarking or hiding schemes usually embed secret data by modifying the BTC encoding stage or BTC-compressed data,obtaining the watermarked image with poorer quality than the BTC-compressed version.This paper presents a new oblivious image watermarking scheme by exploiting BTC bitmaps.Unlike the traditional schemes,our approach does not really perform the BTC compression on images during the embedding process but utilizes the parity of the number of horizontal edge transitions in each BTC bitmap to guide the watermark embedding and extraction processes.The embedding process starts by partitioning the original cover image into non-overlapping 4×4 blocks and performing BTC on each block to obtain its BTC bitmap.One watermark bit is embedded in each block by modifying at most three pixel values in the block to make sure that the parity of the number of horizontal edge transitions in the bitmap of the modified block is equal to the embedded watermark bit.In the extraction stage,the suspicious image is first partitioned into non-overlapping 4×4 blocks and BTC is performed on each block to obtain its bitmap.Then,by checking the parity of the number of horizontal edge transitions in the bitmap,we can extract one watermark bit in each block.Experimental results demonstrate that the proposed watermarking scheme is fragile to various image processing operations while keeping the transparency very well.     

Hiding iris data for authentication of digital images using wavelet theory

This paper introduces an efficient approach to protect the ownership by hiding an iris data into digital image for an authentication purpose. It is based on the theory of wavelets. The idea is to secretly embed biometric data (iris print) in the content of the image identifying the owner. The system is based on an empirical analysis of biometric and watermarking technologies, and it is split into several processes. The first process is based on iris image analysis, which aids the generation of the iris code (watermark); the second and the third processes deal with embedding and detecting a watermark; and the last process deals with the authentication. A new metric that measures the objective quality of the image based on the detected watermark bit is introduced, which does not require the original unmarked image for watermark detection. Simulation results show the effectiveness and efficiency of the proposed approach. The text was submitted by the author in English.     

一种基于纠错编码的可逆文本水印算法

针对现有可逆文本水印抗同义词替换攻击鲁棒性不强的缺点,提出一种基于纠错编码的可逆文本水印算法。利用纠错编码方法,对同义词库中同义词的位置进行编码生成同义词词码字,结合同义词替换技术完成水印的嵌入;在提取水印时,利用纠错码的检测纠错功能完成水印的提取,同时实现同义词替换后可还原的可逆文本水印功能。仿真实验表明,算法嵌入的水印具有良好的不可见性和较强的鲁棒性。     

一种新的MDCT快速算法

改进型的离散余弦变换（Modified disrete cosine transform）作为良好的时频分析工具在单频编码中广泛应用。本文提出了一种基于快速DCT变换的MDCT快速算法,与其他文献的算法相比,其运算量明显减少。     

一种基于音频特征的自适应量化数字音频水印算法

针对传统的固定步长量化方法对不同种类音频载体适应性较差的缺点,提出了一种新的自适应量化步长的数字音频盲水印算法．该算法结合音频载体自身特点自适应确定量化步长,大大增强了算法对不同音频载体的适应性．仿真实验表明,该算法对于不同种类音频载体不仅具有较好的不可感知性,并且对于重采样,重量化,噪声,低通滤波及MP3压缩等攻击都具有较好的鲁棒性.     

抵抗多种攻击的视频水印新方案

随着多媒体技术的发展,数字视频的版权保护变得越来越重要.为了设计一种更加实用的数字视频水印,提出了集成多种技术的、对多种攻击鲁棒的自适应、盲检测视频水印新算法.首先,利用Arnold置乱技术将水印置乱,并进行Turbo编码,以提高其安全性;然后,根据视频的特征,即归纳的频率敏感性、色度敏感性、运动敏感性、纹理敏感性和亮度敏感性选取关键帧,并运用分块技术将关键帧进行3维分块;再进行3维小波分解,选中低频区域作为嵌入域;此外,为了抵抗旋转、缩放攻击,采用了一种新方法,即用Zernike矩提取视频的旋转、缩放不变信息;最后采用盲检测技术提取水印.通过对典型视频数据的攻击和测试,得出了水印的鲁棒性指标.结果表明,本文水印适合多种内容特点的视频,能够抵抗目前常见的各类攻击,具有一定的实用价值.     

基于AT89C2051的单户可视对讲门铃室内分机的设计

本文介绍一种基于单片机AT89C2501的单户可视对讲门铃室内分机的工作原理及软、硬件的设计与实现方法。     

基于期望最大化算法的音频取证中的篡改检测

音频取证中的插值检测是信号篡改检测的重要方面。因为信号的篡改经常伴随着重采样操作,而重采样后的插值信号会引入周期性信息。应用期望最大化（EM）算法能针对这种周期信息估计参数,从而检测出信号是否被篡改。为了使EM算法迭代效果更好,更适用于音频信号的插值检测问题,提出针对音频信号的特点,引入音频幅度直方图,排除短时静音和增加样本点数的方法。另外还提出了用频谱统计矩作为特征的方法,使统计分类稳定有效。最后通过音频取证中检测信号是否重采样的统计分类实验,表明整个检测流程能达到较高的准确率,并且在局部篡改实验中也同样有效。