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Vegetation field spectrum denoising via lifting wavelet transform
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作者 周广柱 杨锋杰 王翠珍 《Journal of Coal Science & Engineering(China)》 2008年第1期131-135,共5页
Field spectrum pretreatment experiments were carried out, and denoising numerical experiment via lifting wavelet transform (LWT) was designed, and several famous test signals including blocks, bumps, heavy sine and ... Field spectrum pretreatment experiments were carried out, and denoising numerical experiment via lifting wavelet transform (LWT) was designed, and several famous test signals including blocks, bumps, heavy sine and doppler were processed via Lw'r in these experiment. And the field spectrum was processed via Lw'r. Experiments proved that SNRG-tO-SNRN curves have similar feature and they all have a peak. And SNRG of almost all employed wavelets have higher value with SNRN between 0 and 20 dB. When signal is at high SNR, the SNRG is very little, and the MSED of denoised signal became little by little. LWT is more suite to denoise the low SNR or heavy noise contaminated signals. Bior4.4 have wider SNRN interval for denoising comparing with other five wavelets, includ- ing haar, db6, sym6, bior2.2 and bior3.3. Original field spectrum is processed by 3 stage liftings based on bior4.4 to denoise the trivial noise-contaminated regions. On processing the water band signal, logarithm transform is firstly taken. And then the spectrum is denoised via LWT based on bior4.4. The results show that an excellent denoised spectrum can be get, especially between 350 nm and 1 800 nm, and between 1 960 nm to 2 500 nm. While there is still a bump around 1 900 nm, this maybe due to the spectrum machine's limited precision. 展开更多
关键词 vegetation field spectrum lifting wavelet transform DENOISE numerical ex-periment
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A COMPRESSION ALGORITHM FOR ECG BASED ON INTEGER LIFTING SCHEME WAVELET TRANSFORM
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作者 Zhang Kunyan Guo Yinjing Lü Wenhong Sun Jinping Wang Xiuzhen 《Journal of Electronics(China)》 2007年第5期674-678,共5页
In view of the shortcomes of conventional ElectroCardioGram (ECG) compression algo- rithms,such as high complexity of operation and distortion of reconstructed signal,a new ECG compression encoding algorithm based on ... In view of the shortcomes of conventional ElectroCardioGram (ECG) compression algo- rithms,such as high complexity of operation and distortion of reconstructed signal,a new ECG compression encoding algorithm based on Set Partitioning In Hierarchical Trees (SPIHT) is brought out after studying the integer lifting scheme wavelet transform in detail.The proposed algorithm modifies zero-tree structure of SPIHT,establishes single dimensional wavelet coefficient tree of ECG signals and enhances the efficiency of SPIHT-encoding by distributing bits rationally,improving zero-tree set and ameliorating classifying method.For this improved algorithm,floating-point com- putation and storage are left out of consideration and it is easy to be implemented by hardware and software.Experimental results prove that the new algorithm has admirable features of low complexity, high speed and good performance in signal reconstruction.High compression ratio is obtained with high signal fidelity as well. 展开更多
关键词 Electro Cardio Gram (ECG) Integer lifting scheme wavelet transform Set Partitioning InHierarchical Trees (SPIHT)
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基于LWT的可见光OFDM-IM系统研究
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作者 王宁 赵黎 +1 位作者 张峰 孟祥艳 《激光杂志》 CAS 北大核心 2024年第1期148-153,共6页
针对索引调制正交频分复用(OFDM-IM)技术峰均比过高,对相位噪声和载波频偏敏感,系统复杂度高等问题,提出基于小波提升变换(LWT)的可见光OFDM-IM系统。首先选择正交小波基作为子载波,通过对信号的分裂、预测和更新,将信号分为高频信号和... 针对索引调制正交频分复用(OFDM-IM)技术峰均比过高,对相位噪声和载波频偏敏感,系统复杂度高等问题,提出基于小波提升变换(LWT)的可见光OFDM-IM系统。首先选择正交小波基作为子载波,通过对信号的分裂、预测和更新,将信号分为高频信号和低频信号,再结合可见光信道构成LWT-OFDM-IM系统,最后通过理论分析和蒙特卡罗方法对系统的可靠性、峰均比特性和最佳小波分解层数进行了仿真验证,结果表明:当子载波N=256,子块中子载波数量L=4,激活子载波数量k=2,系统误码率为10~(-4)时,LWT-OFDM-IM比FFT-OFDM-IM改善约8 dB,相较于DWT-OFDM-IM提高约4 dB。当系统互补累计分布函数(CCDF)为10^(-1)数量级时,LWT-OFDM-IM的峰均比较FFT-OFDM-IM改善约2.3 dB。随着小波层数的递增,系统的误码性能越好,当小波层数为3层时,大约在10 dB附近,误码率可到10^(-5)量级。 展开更多
关键词 可见光通信 正交频分复用 提升小波变换 索引调制 峰均比
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Multiple description scalable video coding based on 3D lifted wavelet transform 被引量:3
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作者 KIM Yong-deak 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第5期857-863,共7页
In this work, a new method to deal with the unconnected pixels in motion compensated temporal filtering (MCTF) is presented, which is designed to improve the performance of 3D lifted wavelet coding. Furthermore, multi... In this work, a new method to deal with the unconnected pixels in motion compensated temporal filtering (MCTF) is presented, which is designed to improve the performance of 3D lifted wavelet coding. Furthermore, multiple description scalable coding (MDSC) is investigated, and novel MDSC schemes based on 3D wavelet coding are proposed, using the lifting imple- mentation of temporal filtering. The proposed MDSC schemes can avoid the mismatch problem in multiple description video coding, and have high scalability and robustness of video transmission. Experimental results showed that the proposed schemes are feasible and adequately effective. 展开更多
关键词 Multiple description SCALABLE coding (MDSC) MOTION compensated temporal filtering (MCTF) Block-split bidi-rectional MOTION estimation 3D lifted wavelet transform
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小波分频自注意力Transformer图像去雨网络 被引量:3
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作者 方思严 刘斌 《计算机工程与应用》 CSCD 北大核心 2024年第6期259-273,共15页
针对视觉Transformer对高频信息捕捉能力弱以及目前许多图像去雨方法易丢失细节的问题,提出小波分频自注意力Transformer图像去雨网络(WFDST-Net)。小波分频自注意力Transformer(WFDST)作为WFDST-Net的主要模块,其利用不可分提升小波变... 针对视觉Transformer对高频信息捕捉能力弱以及目前许多图像去雨方法易丢失细节的问题,提出小波分频自注意力Transformer图像去雨网络(WFDST-Net)。小波分频自注意力Transformer(WFDST)作为WFDST-Net的主要模块,其利用不可分提升小波变换获取特征图的低频分量和高频分量,分别在低频和高频中进行自注意力交互,使模块从低频中学习恢复全局结构的能力,在高频中强化捕捉雨纹等线条细节的能力,增强对不同频域特征的建模能力。WFDST-Net采用U形架构并通过不可分提升小波变换获取多尺度特征,可在捕获不同形状高频雨纹的同时保证信息的完整性。相比其他图像去雨相关的Transformer,WFDST-Net具有更低的参数量。此外,提出VOCRain250数据集用于联合图像去雨和语义分割任务,该数据集比目前广泛使用的BDD150更具优势。实验表明,所提方法增强了视觉Transformer对不同频域信息的捕获能力,并在合成和真实数据集以及VOCRain250中的表现优于目前先进的去雨方法,能有效去除复杂雨纹并保留更多细节特征。 展开更多
关键词 图像去雨 transformER 自注意力 不可分提升小波 频域
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Seismic data compression based on integer wavelet transform 被引量:1
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作者 WANG Xi-zhen(王喜珍) TENG Yun-tian(滕云田) +1 位作者 GAO Meng-tan(高孟潭) JIANG Hui(姜慧) 《Acta Seismologica Sinica(English Edition)》 CSCD 2004年第z1期123-128,共6页
Due to the particularity of the seismic data, they must be treated by lossless compression algorithm in some cases. In the paper, based on the integer wavelet transform, the lossless compression algorithm is studied.... Due to the particularity of the seismic data, they must be treated by lossless compression algorithm in some cases. In the paper, based on the integer wavelet transform, the lossless compression algorithm is studied. Comparing with the traditional algorithm, it can better improve the compression rate. CDF (2, n) biorthogonal wavelet family can lead to better compression ratio than other CDF family, SWE and CRF, which is owe to its capability in can- celing data redundancies and focusing data characteristics. CDF (2, n) family is suitable as the wavelet function of the lossless compression seismic data. 展开更多
关键词 lossless compression integer wavelet transform lifting scheme biorthogonal wavelet
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AN EFFICIENT 3-DIMENSIONAL DISCRETE WAVELET TRANSFORM ARCHITECTURE FOR VIDEO PROCESSING APPLICATION 被引量:1
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作者 Ganapathi Hegde Pukhraj Vaya 《Journal of Electronics(China)》 2012年第6期534-540,共7页
This paper presents an optimized 3-D Discrete Wavelet Transform (3-DDWT) architecture. 1-DDWT employed for the design of 3-DDWT architecture uses reduced lifting scheme approach. Further the architecture is optimized ... This paper presents an optimized 3-D Discrete Wavelet Transform (3-DDWT) architecture. 1-DDWT employed for the design of 3-DDWT architecture uses reduced lifting scheme approach. Further the architecture is optimized by applying block enabling technique, scaling, and rounding of the filter coefficients. The proposed architecture uses biorthogonal (9/7) wavelet filter. The architecture is modeled using Verilog HDL, simulated using ModelSim, synthesized using Xilinx ISE and finally implemented on Virtex-5 FPGA. The proposed 3-DDWT architecture has slice register utilization of 5%, operating frequency of 396 MHz and a power consumption of 0.45 W. 展开更多
关键词 3-D Discrete wavelet transform (3-DDWT) lifting scheme PIPELINING Video coding Low power
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Low complexity reconfigurable architecture for the 5/3 and 9/7 discrete wavelet transform
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作者 Xiong Cheng yi Tian Jinwen Liu Jian 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2006年第2期303-308,共6页
Efficient reconfigurable VLSI architecture for 1-D 5/3 and 9/7 wavelet transforms adopted in JPEG2000 proposal, based on lifting scheme is proposed. The embedded decimation technique based on fold and time multiplexin... Efficient reconfigurable VLSI architecture for 1-D 5/3 and 9/7 wavelet transforms adopted in JPEG2000 proposal, based on lifting scheme is proposed. The embedded decimation technique based on fold and time multiplexing, as well as embedded boundary data extension technique, is adopted to optimize the design of the architecture. These reduce significantly the required numbers of the multipliers, adders and registers, as well as the amount of accessing external memory, and lead to decrease efficiently the hardware cost and power consumption of the design. The architecture is designed to generate an output per clock cycle, and the detailed component and the approximation of the input signal are available alternately. Experimental simulation and comparison results are presented, which demonstrate that the proposed architecture has lower hardware complexity, thus it is adapted for embedded applications. The presented architecture is simple, regular and scalable, and well suited for VLSI implementation. 展开更多
关键词 VLSI discrete wavelet transform lifting scheme embedded decimation reeonfigurable.
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New Edge-Directed Interpolation Based-Lifting DWT and MSPIHT Algorithm for Image Compression 被引量:1
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作者 M. Varathaguru R. S. Sabeenian 《Circuits and Systems》 2016年第9期2242-2252,共12页
The amount of image data generated in multimedia applications is ever increasing. The image compression plays vital role in multimedia applications. The ultimate aim of image compression is to reduce storage space wit... The amount of image data generated in multimedia applications is ever increasing. The image compression plays vital role in multimedia applications. The ultimate aim of image compression is to reduce storage space without degrading image quality. Compression is required whenever the data handled is huge they may be required to sent or transmitted and also stored. The New Edge Directed Interpolation (NEDI)-based lifting Discrete Wavelet Transfrom (DWT) scheme with modified Set Partitioning In Hierarchical Trees (MSPIHT) algorithm is proposed in this paper. The NEDI algorithm gives good visual quality image particularly at edges. The main objective of this paper is to be preserving the edges while performing image compression which is a challenging task. The NEDI with lifting DWT has achieved 99.18% energy level in the low frequency ranges which has 1.07% higher than 5/3 Wavelet decomposition and 0.94% higher than traditional DWT. To implement this NEDI with Lifting DWT along with MSPIHT algorithm which gives higher Peak Signal to Noise Ratio (PSNR) value and minimum Mean Square Error (MSE) and hence better image quality. The experimental results proved that the proposed method gives better PSNR value (39.40 dB for rate 0.9 bpp without arithmetic coding) and minimum MSE value is 7.4. 展开更多
关键词 lifting Discrete wavelet transform (DWT) Image Compression Set Partitioning in Hierarchical Trees (SPIHT) New Edge Directed Interpolation (NEDI)
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An Approach to Integer Wavelet Transform for Medical Image Compression in PACS
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作者 YANG Yan ZHANG Dong 《Wuhan University Journal of Natural Sciences》 CAS 2000年第2期204-206,共3页
We study an approach to integer wavelet transform for lossless compression of medical image in medical picture archiving and communication system (PACS). By lifting scheme a reversible integer wavelet transform is gen... We study an approach to integer wavelet transform for lossless compression of medical image in medical picture archiving and communication system (PACS). By lifting scheme a reversible integer wavelet transform is generated, which has the similar features with the corresponding biorthogonal wavelet transform. Experimental results of the method based on integer wavelet transform are given to show better performance and great applicable potentiality in medical image compression. 展开更多
关键词 Key words integer wavelet transform lifting scheme lossless compression PACS
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Lifting Scheme and Its Application to Edge Detection
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作者 Yang Yan +2 位作者 Qin Qian-qing 《Wuhan University Journal of Natural Sciences》 CAS 2003年第01A期74-76,共3页
Lifting scheme is a useful and very general technique for constructing wavelet decomposition. The paper adapts the lifting into redundant lifting to obtain shift invariant wavelet transform. ... Lifting scheme is a useful and very general technique for constructing wavelet decomposition. The paper adapts the lifting into redundant lifting to obtain shift invariant wavelet transform. In prediction and update stages of the lifting morphological operator is adopted for preserving local maxima of a signal over several scales, which is particularly useful in wavelet\|based signal detec tion. The new transform presented in the paper is applied in multiresoluti on edge detection of medical image and experim ent results are given to show better performance and applicable potentiali ty. 展开更多
关键词 lifting scheme redundant wavelet transform morpholog ical operator edge detection
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An Image Fusion Algorithm Based on Lifting Scheme
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作者 BAI Di FAN Qibin SHU Qian 《Geo-Spatial Information Science》 2005年第3期171-175,200,共6页
Taking the advantage of the lifting scheme's characters that can build wavelet translorms tor transforming from integer to integer and the quality of the reconstructing image'is independent of the topology way adopt... Taking the advantage of the lifting scheme's characters that can build wavelet translorms tor transforming from integer to integer and the quality of the reconstructing image'is independent of the topology way adopted by the boundary, an image fusion algorithm based on lifting scheme is proposed. This paper discusses the fundamental theory of lifting scheme firstly and then after taking transform analysis according to a kind of images that need to be confused. 展开更多
关键词 lifting schemes image processing integer wavelet transform image fusion
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A Parallel-based Lifting Algorithm and VLSI Architecture for DWT
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作者 Xiong Chengyi Tian Jinwen +1 位作者 Liu Jian Gao Zhirong 《Journal of Electronics(China)》 2006年第2期244-248,共5页
A novel Parallel-Based Lifting Algorithm (PBLA) for Discrete Wavelet Transform (DWT), exploiting the parallelism of arithmetic operations in all lifting steps, is proposed in this paper. It leads to reduce the cri... A novel Parallel-Based Lifting Algorithm (PBLA) for Discrete Wavelet Transform (DWT), exploiting the parallelism of arithmetic operations in all lifting steps, is proposed in this paper. It leads to reduce the critical path latency of computation, and to reduce the complexity of hardware implementation as well. The detailed derivation on the proposed algorithm, as well as the resulting Very Large Scale Integration (VLSI) architecture, is introduced, taking the 9/7 DWT as an example but without loss of generality. In comparison with the Conventional Lifting Algorithm Based Implementation (CLABI), the critical path latency of the proposed architecture is reduced by more than half from (4Tm + 8Ta)to Tm + 4Ta, and is competitive to that of Convolution-Based Implementation (CBI), but the new implementation will save significantly in hardware. The experimental results demonstrate that the proposed architecture has good performance in both increasing working frequency and reducing area. 展开更多
关键词 Discrete wavelet transform (DFT) lifting scheme PARALLEL Very Large Scale Integration(VLSI)
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基于LWT-OFDM的NOMA-VLC系统
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作者 樊欣 张峰 赵黎 《光通信技术》 2023年第6期6-10,共5页
针对基于傅里叶变换光正交频分复用(FFT-OFDM)的非正交多址可见光通信(NOMA-VLC)系统存在可靠性低、用户公平性差等问题,提出将提升小波变换(LWT)作为载波调制方式,建立基于LWT-OFDM的NOMA-VLC系统,介绍了系统中的信号处理过程,构建了5 ... 针对基于傅里叶变换光正交频分复用(FFT-OFDM)的非正交多址可见光通信(NOMA-VLC)系统存在可靠性低、用户公平性差等问题,提出将提升小波变换(LWT)作为载波调制方式,建立基于LWT-OFDM的NOMA-VLC系统,介绍了系统中的信号处理过程,构建了5 m×5 m×3 m的室内空间实验环境。实验结果表明:与基于FFT-OFDM的NOMA-VLC系统相比,随着正交幅度调制方式的阶次由4增大到64,所提系统的平均误码率达到阀值3.8×10^(-3)时,所需的信噪比(SNR)值较低,至少低4.4 dB;用户性能差异变化不明显甚至不变。 展开更多
关键词 光通信 非正交多址 提升小波变换 可靠性 用户公平性
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Robust Image Watermarking Using LWT and Stochastic Gradient Firefly Algorithm
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作者 Sachin Sharma Meena Malik +3 位作者 Chander Prabha Amal Al-Rasheed Mona Alduailij Sultan Almakdi 《Computers, Materials & Continua》 SCIE EI 2023年第4期393-407,共15页
Watermarking of digital images is required in diversified applicationsranging from medical imaging to commercial images used over the web.Usually, the copyright information is embossed over the image in the form ofa l... Watermarking of digital images is required in diversified applicationsranging from medical imaging to commercial images used over the web.Usually, the copyright information is embossed over the image in the form ofa logo at the corner or diagonal text in the background. However, this formof visible watermarking is not suitable for a large class of applications. In allsuch cases, a hidden watermark is embedded inside the original image as proofof ownership. A large number of techniques and algorithms are proposedby researchers for invisible watermarking. In this paper, we focus on issuesthat are critical for security aspects in the most common domains like digitalphotography copyrighting, online image stores, etc. The requirements of thisclass of application include robustness (resistance to attack), blindness (directextraction without original image), high embedding capacity, high Peak Signalto Noise Ratio (PSNR), and high Structural Similarity Matrix (SSIM). Mostof these requirements are conflicting, which means that an attempt to maximizeone requirement harms the other. In this paper, a blind type of imagewatermarking scheme is proposed using Lifting Wavelet Transform (LWT)as the baseline. Using this technique, custom binary watermarks in the formof a binary string can be embedded. Hu’s Invariant moments’ coefficientsare used as a key to extract the watermark. A Stochastic variant of theFirefly algorithm (FA) is used for the optimization of the technique. Undera prespecified size of embedding data, high PSNR and SSIM are obtainedusing the Stochastic Gradient variant of the Firefly technique. The simulationis done using Matrix Laboratory (MATLAB) tool and it is shown that theproposed technique outperforms the benchmark techniques of watermarkingconsidering PSNR and SSIM as quality metrics. 展开更多
关键词 Image watermarking lifting wavelet transform discrete wavelet transform(DWT) firefly technique invariant moments
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基于多通道的彩色图像多重水印算法
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作者 郑秋梅 赵丹 +1 位作者 牛薇薇 林超 《计算机工程》 CAS CSCD 北大核心 2024年第9期246-254,共9页
针对多重水印技术如何确定最优的嵌入区域,以实现多个水印之间的权衡问题,提出一种基于多通道嵌入的彩色图像多重水印算法。当嵌入水印时,选择在彩色图像R、G、B 3个通道嵌入不同的水印图像,目的是嵌入更多的水印信息。通过提升小波变换... 针对多重水印技术如何确定最优的嵌入区域,以实现多个水印之间的权衡问题,提出一种基于多通道嵌入的彩色图像多重水印算法。当嵌入水印时,选择在彩色图像R、G、B 3个通道嵌入不同的水印图像,目的是嵌入更多的水印信息。通过提升小波变换(LWT)和非下采样剪切波变换(NSST)提取宿主图像每个通道中的方向性特征,确定水印的嵌入位置,以提高对常规攻击和几何攻击的鲁棒性。通过将加密的水印有效信息嵌入到具有良好稳定性的奇异值矩阵中,保证水印的提取效果。实验结果表明,嵌入水印后的图像峰值信噪比(PSNR)在43 dB以上,所提算法具备良好的不可见性,对嵌入水印后的图像进行高强度的旋转、滤波、剪切等攻击,提取水印的归一化系数(NC)值在0.95以上,其中,滤波攻击对应的NC值可以达到0.99以上,水印信息提取完整、清晰可辨,表现出较强的鲁棒性。同时,该算法可以1次嵌入3个水印图像,具有更高的嵌入容量。因此,与现有的多重水印算法相比,该算法的不可见性、鲁棒性和嵌入容量均有较大的提升。 展开更多
关键词 多重水印 提升小波变换 非下采样剪切波变换 鲁棒性 嵌入容量
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一种新的LWT和SVD的灰度图像水印 被引量:4
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作者 蒋华 张敏 《计算机工程与应用》 CSCD 北大核心 2010年第11期104-106,108,共4页
先对载体图像进行分块,然后对每块二级LWT后的中高频带再次LWT,并对选取的各频带进行SVD,选取其相应的奇异值组成新的变换矩阵,对新的变换矩阵按规则进行分块,并再次SVD。通过两次分块,两次LWT和四重使用SVD构造矩阵的方法,有效地将抽... 先对载体图像进行分块,然后对每块二级LWT后的中高频带再次LWT,并对选取的各频带进行SVD,选取其相应的奇异值组成新的变换矩阵,对新的变换矩阵按规则进行分块,并再次SVD。通过两次分块,两次LWT和四重使用SVD构造矩阵的方法,有效地将抽取的奇异值重新分配和组合,最后将Arnold置乱后的灰度水印信息加载到组合后的矩阵中。仿真实验表明,新的图像水印方法提高了嵌入的信息量,具有很好的透明性,而且对常见的图像攻击具有很强的鲁棒性。 展开更多
关键词 提升小波变换 奇异值分解 ARNOLD置乱 透明性 鲁棒性
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基于LWT-DCT-QR混合域的音频信号水印算法 被引量:5
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作者 虞文进 徐培富 +1 位作者 王文娟 叶志晖 《实验室研究与探索》 CAS 北大核心 2017年第3期26-30,共5页
为提高音频水印的鲁棒性,设计了一种基于LWT-DCT-QR混合域的水印嵌入方法,充分发挥提升小波变换运算速度快、离散余弦变换抗干扰能力强以及QR分解数值稳定性好的特点,并通过Logistic混沌序列进行加密,从而实现水印图像的嵌入与提取。通... 为提高音频水印的鲁棒性,设计了一种基于LWT-DCT-QR混合域的水印嵌入方法,充分发挥提升小波变换运算速度快、离散余弦变换抗干扰能力强以及QR分解数值稳定性好的特点,并通过Logistic混沌序列进行加密,从而实现水印图像的嵌入与提取。通过噪声、采样、滤波、剪切、压缩等攻击对水印的安全性、不可感知性以及鲁棒性进行了仿真与测试,并利用水印信号的相关系数(NC)和信噪比(SNR)进行分析评定。测试结果表明,所提出的水印算法具有较强的抗攻击能力,与相关文献相比具有一定的优越性。 展开更多
关键词 音频水印 提升小波变换 离散余弦变换 QR分解
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基于LWT的可见光DCO-OFDM系统 被引量:10
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作者 赵黎 董航航 张峰 《光子学报》 EI CAS CSCD 北大核心 2021年第5期121-129,共9页
为了解决传统正交频分复用技术峰均比过高、复值型信号结构无法直接应用于强度调制直接检测系统等问题,将提升小波变换(LWT)应用于正交频分复用(OFDM)中,选择正交小波基作为子载波,通过对信号的预测与更新,将信号的高低频分离,并结合可... 为了解决传统正交频分复用技术峰均比过高、复值型信号结构无法直接应用于强度调制直接检测系统等问题,将提升小波变换(LWT)应用于正交频分复用(OFDM)中,选择正交小波基作为子载波,通过对信号的预测与更新,将信号的高低频分离,并结合可见光通信(VLC)多次反射信道模型,建立了DCO-LWT-OFDM系统模型,推导了LWT-OFDM信号迭代分解与更新重构公式,对其性能分别进行了仿真分析与实验验证。模拟仿真实验表明,在4 m×4 m×3 m室内空间中,当系统误码率为10^(-4)时,DCO-LWT-OFDM系统较DCO-FFT-OFDM系统的性能大约提高了5 dB,综合效率提高了70%,当系统峰均比为10dB时,DCO-FFT-OFDM系统的互补累积分布函数值接近10^(-1),DCO-LWTOFDM系统的互补累积分布函数值为0。实验验证中,选择1 W LED灯珠在光学导轨上搭建点到点DCO-LWT-OFDM VLC系统,传输距离为20 cm,系统调制误差率为11.4 dB,可靠性可达10^(-4)。本文研究为提高可见光通信的传输速率,降低系统误码率,抑制系统峰均比提供了一种有效途径。 展开更多
关键词 可见光通信 正交频分复用 提升小波变换 误码率 通信效率
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基于LWT-SVD的鲁棒自适应水印方案 被引量:4
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作者 熊祥光 曾文权 《计算机工程与设计》 北大核心 2015年第6期1494-1497,1503,共5页
为进一步提高水印抵抗攻击的能力,提出一种基于量化的混合提升小波变换和奇异值分解的自适应数字图像水印算法。对二值水印信号进行异或加密与置乱处理,以增强水印信号的安全性和鲁棒性;对原始载体图像进行互不重叠的分块,对随机选取的... 为进一步提高水印抵抗攻击的能力,提出一种基于量化的混合提升小波变换和奇异值分解的自适应数字图像水印算法。对二值水印信号进行异或加密与置乱处理,以增强水印信号的安全性和鲁棒性;对原始载体图像进行互不重叠的分块,对随机选取的分块进行一级提升小波变换,对生成的低频子带进行奇异值分解;根据水印信号的取值,对每一分块低频子带的最大奇异值采用自适应量化的方法嵌入水印信号。仿真结果表明,该算法具有较好的透明性和抵抗常规信号处理攻击的能力。 展开更多
关键词 图像水印 奇异值分解 提升小波变换 量化 鲁棒性 盲提取
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