一种基于DWT的数字水印算法

提出了一种基于离散小波变换的数字水印算法,选择低频子带嵌入水印,保证了水印的不可见性;该算法选择了对JPEG2000彩色多分量图像的Y分量嵌入Arnold变换水印,简化了水印的检测。实验结果表明,该方案能抵御压缩、模糊和锐化等攻击,具有较好的鲁棒性。     

基于DWT的音频"零数字"水印技术研究

提出了一种改进的方法,即在不修改音频数据情况下把水印信息＂嵌入＂到原始信号中.实验证明,该方法能够有效抵御各种常见攻击,具有很强的鲁棒性,并且在提取水印的时候可以不需要原始信号.     

小波变换硬件实现中有限字长效应的分析

对小波变换硬件实现有限字长的产生和影响进行分析,并提出解决方法。对JPEG2000压缩编码标准中5／3和9／7小波变换,提出采用分数逼近小数的方法实现,比较小数系数和分数系数的变换结果,证明采用分数格式可以在有效的降低硬件实现复杂性的同时,提供相近的变换结果;通过扩大原始信号(左移若干比特)和对中间结果进行合理舍入的方法减小硬件实现中有限字长对变换精度的影响。     

基于形态滤波的小波融合图像增强算法

研究图像优化问题。针对目前常用的空域或频域图像存在各种噪声干扰降低了图像的清晰度,为了在降低图像噪声,保护图像细节和边缘信息,提出一种形态滤波的小波融合图像增强算法MWF。首先分别采用巴特沃斯低通滤波和形态学高帽处理对含噪图像进行滤波,得到两幅过滤的图像,再将这两幅图像分别进行离散小波变换,然后利用变换结果在小波域内依据融合规则进行融合,最后对融合结果进行反变换得到清晰的图像。得到的图像是通过空域滤波和频域增强方法的结合,综合了两种方法各自的优点,仿真结果表明,MWF算法对混合噪声干扰有较好的抑制作用,并实现了图像增强的效果,为图像优化提供了依据。     

小波域内图象零水印技术的研究

为了在保证图象质量的前提下实施图象的版权保护，提出了一种图象零水印方法．该方法改变了传统的向原始图象中嵌入水印信息来实现版权保护的做法，采用从图象中抽取水印信息的方法来实现这一功能，其核心思想是：恰当选取图象小波变换的系数，然后把它作为原始图象的基本信息进行定位和管理，当对待认证图象进行认证时，用同样的方法提取该认证图象的信息，并对这些信息进行分析和检测，从而判定该图象的版权和所有权．通过实验证明，这种方法具有无失真、鲁棒性好、简单易行及可操作性强等优点．最后对该方法进行了推广，使它不但可以从原图象中提取水印，而且可以在图象外部加载水印，该方法既能满足图象认证的需要，又能用来进行数据隐藏．     

基于子波变换的一种信号除噪新算法研究

针对Donoho去噪算法中阈值难以确定，通过分析白噪声的能量分布在于波变换域随尺度变化的规律，提出了一种采用子波变换来消除信号噪声的新算法。通过对含噪信号的求导运算实现信号与噪声在于波变换域约分离，以达到消除噪声的目的，算法的特点在于能够自动给出信号中噪声的阈值。经过测试，该算法在消除信号中的白噪声时，能够取得比较理想的效果。     

小波变换和SHA-1相结合的图像压缩加密

针对图像分层树集划分编码的安全性问题,提出一种将小波变换和SHA-1(security hash algorithm-1)相结合的图像加密算法(DSCE).首先将图像小波变换后的系数分为低频和高频两部分,然后将低频系数、初始密钥及图像像素和,通过SHA-1置乱加密SPIHT编码高频系数;将部分加密高频系数和初始密钥,通过SHA-1置乱加密Huff man编码低频系数,在压缩过程中实现低频和高频部分相互加密.仿真结果表明,DSCE算法密钥空间大,对密钥和明文敏感,同时有效提高图像存储和传输效率.     

基于离散小波变换的信号分解与重构

为数值计算简化和理论分析简便,在实际信号处理应用中,需要对小波变换进行离散化处理。介绍了傅里叶变换与小波变换的基本理论,以及离散小波变换在信号分解和重构过程中的原理及方法。利用MATLAB小波工具箱中提供的函数分别对一维信号和语音信号进行分解与完全重构,并对结果进行分析比较。仿真结果表明,用离散小波变换进行一维和语音信号分解时均可有效地获取其平均相似信息和细节信息,重构信号与原始信号相比损失较少,分解和重构均得到了很好的效果。     

A new music-empirical wavelet transform methodology for time–frequency analysis of noisy nonlinear and non-stationary signals

The goal of signal processing is to estimate the contained frequencies and extract subtle changes in the signals. In this paper, a new adaptive multiple signal classification-empirical wavelet transform (MUSIC-EWT) methodology is presented for accurate time–frequency representation of noisy non-stationary and nonlinear signals. It uses the MUSIC algorithm to estimate the contained frequencies in the signal and build the appropriate boundaries to create the wavelet filter bank. Then, the EWT decomposes the time-series signal into a set of frequency bands according to the estimated boundaries. Finally, the Hilbert transform is applied to observe the evolution of calculated frequency bands over time. The usefulness and effectiveness of the proposed methodology are validated using two simulated signals and an ECG signal obtained experimentally. The results demonstrate clearly that the proposed methodology is immune to noise and capable of estimating the optimal boundaries to isolate the frequencies from noise and estimate the main frequencies with high accuracy, especially the closely-spaced frequencies.     

Hardware and software architecture for power quality analysis

This paper presents a novel concept for power quality hardware and software architecture. Software tools related to detection, classification and characterization of power quality events can be integrated into a Distribution Control Center in which the interconnection between different subsystems is being carried out through the Internet allowing flexibility to the system. This system is implemented using wavelet analysis applied in all proposed algorithms. Different power quality events are taken as examples to illustrate the capabilities of the proposed method. The obtained results reveal that the proposed architecture is feasible to be implemented as an integral part of a control center system.The proposed system has the property of fast and accurate detection and classification of any power quality disturbance event and introduces a new PQ index determination that allows characterizing any type of disturbance including the non-periodic signals.     

基于小波分析的传感器故障诊断方法仿真研究

针对装甲车辆数据采集控制系统中传感器故障难于直接检测的问题,本文提出一种基于小波变换的方法对传感器故障进行诊断。首先介绍了小波分析的基本理论,对比阐述了连续小波变换和离散小波变换的原理和优缺点;其次利用Matlab/Simulink搭建模型进行仿真试验,采用连续小波变换对传感器故障进行检测,准确定位故障发生时刻;最后本文还选取了几种典型的传感器故障进行诊断,仿真结果验证了该方法的可行性和准确性。     

A novel license plate location method based on wavelet transform and EMD analysis

Although various license plate location methods have been proposed in the past decades, their accuracy and ability to deal with different types of license plates still need to be improved. A robust license plate location method can raise the accuracy of the whole license plate recognition procedure. This paper proposes a robust method based on wavelet transform and empirical mode decomposition (EMD) analysis to search for the location of a license plate in an image to deal with some challenging problems in practice such as illumination changes, complex background and perspective change. By applying wavelet transform on a vehicle image and projecting the acquired details of the image, a wave crest that indicates the license plate will be generated. In order to locate the desired wave crest in the nonlinear and non-stationary projection dataset, EMD analysis is applied. Using the reconstructed projection data and the Hilbert transform of intrinsic mode function components, the position of the license plate is detected. Comprehensive experiments show that this method can locate the positions of various types of license plates with a high accuracy of 97.91% and a relatively short running time.     

一种精简的二维DWT结构设计

设计了一种低功耗的二维离散小波变换(DWT)结构，用于无线传感器网络中的图像压缩。该结构实现了精简复杂性的(5,3)整数离散小波变换，采用流水线和延迟线技术，在获得高运算吞吐率的同时，使数据尽可能被处理单元高效利用，以减少对片内存储器和片外存储器的访问次数。多级二维DWT采用展开方法实现，这种方法可尽早开始下一级变换，不需要大的片内存储器和片内存取操作。模拟试验和FPGA实现验证了系统在满足需要性能的前提下具有低复杂性、低功耗、片内存储器小等优点。     

Experimental evaluation of fault diagnosis in a skew-configured UAV sensor system

This paper presents an experimental evaluation of a hybrid fault detection and isolation scheme against three successive faults in skew-configured inertial sensors of an unmanned aerial vehicle (UAV). An additional small and low-cost inertial measurement unit is installed with a skewed angle to a primary inertial measurement unit. A parity space method and an in-lane monitoring method are combined to increase system tolerance to the occurrence of multiple successive faults during flight. The first and second faults are detected and isolated by the parity space method. The third fault is detected by the parity space method and isolated by the in-lane monitoring method based on the discrete wavelet transform. Hardware in-the-loop tests and flight experiments with a fixed-wing UAV are performed to verify the performance of the proposed fault diagnosis scheme.     

Retrieval of chlorophyll concentration from leaf reflectance spectra using wavelet analysis

The dynamics of foliar chlorophyll concentrations have considerable significance for plant-environment interactions, ecosystem functioning and crop growth. Hyperspectral remote sensing has a valuable role in the monitoring of such dynamics. This study focussed upon improving the accuracy of chlorophyll quantification by applying wavelet analysis to reflectance spectra. Leaf-scale radiative transfer models were used to generate very large spectral data sets with which to develop and rigorously test refinements to the approach and compare it with existing spectral indices. The results demonstrated that by decomposing leaf spectra, the resultant wavelet coefficients can be used to generate accurate predictions of chlorophyll concentration, despite wide variations in the range of other biochemical and biophysical factors that influence leaf reflectance. Wavelet analysis outperformed predictive models based on untransformed spectra and a range of spectral indices. The paper discusses the possibilities for further refining the wavelet approach and for extending the technique to the sensing of a variety of vegetation properties at a range of spatial scales.     

Destriping Remote Sensing Imagery by Wavelet Moment Matching Algorithm

Strip noise will cover the real radiation information of remote sensing image,which not only reduces image quality,but also application effect.Aiming at the problem that window moment matching is difficult to remove strip noise thoroughly for the non\|uniform image,the wavelet moment matching algorithm is proposed.Firstly,the low frequency wavelet coefficient and the high frequency wavelet coefficients are separated which based on the wavelet multiresolution characteristic.Secondly,the low frequency wavelet coefficients were filtering by window moment matching,while strip noise of high frequency wavelet coefficients was performed by threshold method.Finally,reconstruction of the wavelet coefficients obtained destriping image.The above mentioned algorithm was evaluated quantitatively by local PSNR,local SSIM,Fuzzy coefficient and goodness of fit index.Results show that the wavelet moments matching algorithm is superior to the moment matching,wavelet soft threshold and window moment matching algorithm.Wavelet moment matching improves limitation of uniform distribution of grayscale value based on window moment matching,combining the advantages of spatial and frequency domain denosing,which can remove the noise while preserving the details of the image.     

克服Watershed算法过度分割的方法

Watershed算法是一种形态学的图像分割算法,但由于其对噪声十分敏感,分割结果往往存在过度分割的现象。该文提出一种基于小波分析的Watershed算法,充分利用小波的多分辨率特性有效地解决了Watershed算法的过度分割问题,并大大提高了分割计算速度。     

The facial texture analysis for the automatic portrait drawing

It is important to draw the portrait by the facial textures automatically. In order to analyze the detailed textures located at the neighborhood of the eyes, the texture analyzing method is studied. Firstly, we propose the principle of selecting the feature points and the portrait drawing method by B-spline curves using the self-reference parameter. Then, the wavelet transform is used to analyze the position, the direction and the intensity of the double-fold eyelid textures. Experimental results have shown that the facial texture analyzing method is effective for drawing portraits automatically.     

基于有监督增量式等距离映射的人脸识别

针对等距离映射（Isomap）算法无法对后续采集的测试样本单独进行降维处理和未能利用样本点分类信息的不足,提出了一种有监督的增量式等距离映射算法（SIIsomap）,并采取小波变换对图像进行预处理。通过对ORL数据库实验证明,SIIsomap算法与Isomap算法相比大大降低了处理新增样本点的计算时间,并且提高了识别精度。     

HVS和DWT相结合的数字密写技术研究与实现

提出一种基于人眼视觉系统（HVS）和离散小波变换（DWT）的数字密写算法,结合人眼对遮掩特性的差异,将秘密信息分段嵌入到R、G、B三层的小波中高频系数中,嵌入的顺序按照频带的重要性由低到高嵌入,实验证明,该算法有较好的隐蔽性和较高的嵌入量,通过对彩色图片的数字密写来进行文本信息传输,较好地解决了在互联网上信息传输的通信安全问题。