共查询到20条相似文献,搜索用时 31 毫秒
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B. Mohan Kumar R. Vidhya Lavanya E.P. Sumesh 《International Journal of Electronics》2013,100(3):288-301
Wavelet transform is considered one of the efficient transforms of this decade for real time signal processing. Due to implementation constraints scalar wavelets do not possess the properties such as compact support, regularity, orthogonality and symmetry, which are desirable qualities to provide a good signal to noise ratio (SNR) in case of signal denoising. This leads to the evolution of the new dimension of wavelet called ‘multiwavelets’, which possess more than one scaling and wavelet filters. The architecture implementation of multiwavelets is an emerging area of research. In real time, the signals are in scalar form, which demands the processing architecture to be scalar. But the conventional Donovan Geronimo Hardin Massopust (DGHM) and Chui-Lian (CL) multiwavelets are vectored and are also unbalanced. In this article, the vectored multiwavelet transforms are converted into a scalar form and its architecture is implemented in FPGA (Field Programmable Gate Array) for signal denoising application. The architecture is compared with DGHM multiwavelets architecture in terms of several objective and performance measures. The CL multiwavelets architecture is further optimised for best performance by using DSP48Es. The results show that CL multiwavelet architecture is suited better for the signal denoising application. 相似文献
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The application of multiwavelet filterbanks to image processing 总被引:30,自引:0,他引:30
Strela V. Heller P.N. Strang G. Topiwala P. Heil C. 《IEEE transactions on image processing》1999,8(4):548-563
Multiwavelets are a new addition to the body of wavelet theory. Realizable as matrix-valued filterbanks leading to wavelet bases, multiwavelets offer simultaneous orthogonality, symmetry, and short support, which is not possible with scalar two-channel wavelet systems. After reviewing this theory, we examine the use of multiwavelets in a filterbank setting for discrete-time signal and image processing. Multiwavelets differ from scalar wavelet systems in requiring two or more input streams to the multiwavelet filterbank. We describe two methods (repeated row and approximation/deapproximation) for obtaining such a vector input stream from a one-dimensional (1-D) signal. Algorithms for symmetric extension of signals at boundaries are then developed, and naturally integrated with approximation-based preprocessing. We describe an additional algorithm for multiwavelet processing of two-dimensional (2-D) signals, two rows at a time, and develop a new family of multiwavelets (the constrained pairs) that is well-suited to this approach. This suite of novel techniques is then applied to two basic signal processing problems, denoising via wavelet-shrinkage, and data compression. After developing the approach via model problems in one dimension, we apply multiwavelet processing to images, frequently obtaining performance superior to the comparable scalar wavelet transform. 相似文献
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In this paper, a new approach for classification of brain tissues into White Matter, Gray Matter, Cerebral Spinal Fluid, Glial
Matter, Connective and MS lesion in multiple sclerosis is introduced. This work considers fuzzy multiwavelets, Gaussian Mixture
Model (GMM) and Weighted Probabilistic Neural Networks (WPNN) for the classification of the brain tissues. Multiwavelet packet
transformation is employed on brain MR images. Since multiwavelet packet transformation yields larger number of subbands compared
to multiwavelet and wavelet transformations, we have proposed a fuzzy-set based theory for selection of the subbands. In contrast
to the standard method of subband selection, guided by the criteria of signal energy, our method is based on the discriminatory
features from the multiwavelet packet transformation coefficients. Singular values are then computed from the selected subbands.
The singular values of lower magnitudes are truncated for effective classification of brain tissues in the presence of noise.
Probability density functions of the remaining singular values are modeled as GMM. Model parameters are estimated using stochastic
EM (SEM). They are used as features for the classification. The classification is carried out using WPNN. Experiments have
been carried out using the data sets composed of three modalities of brain MR images, namely T1 and T2 relaxation times and
proton density weighted MR images. Experimental results prove that the proposed approach gives better classification rate
at various noise levels compared to existing approaches. 相似文献
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Data-driven and optimal denoising of a signal and recovery of its derivative using multiwavelets 总被引:4,自引:0,他引:4
Efromovich S. Lakey J. Pereyra M.C. Tymes N. Jr. 《Signal Processing, IEEE Transactions on》2004,52(3):628-635
Multiwavelets are relative newcomers into the world of wavelets. Thus, it has not been a surprise that the used methods of denoising are modified universal thresholding procedures developed for uniwavelets. On the other hand, the specific of a multiwavelet discrete transform is that typical errors are not identically distributed and correlated, whereas the theory of the universal thresholding is based on the assumption of identically distributed and independent normal errors. Thus, we suggest an alternative denoising procedure based on the Efromovich-Pinsker algorithm. We show that this procedure is optimal over a wide class of noise distributions. Moreover, together with a new cristina class of biorthogonal multiwavelets, which is introduced in this paper, the procedure implies an optimal method for recovering the derivative of a noisy signal. A Monte Carlo study supports these conclusions. 相似文献
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多小波的预处理及其在图像压缩中的应用 总被引:13,自引:1,他引:12
多小波是近几年小波理论研究的一个重要方向,但在图像压缩中还没有成功的例子;本文综述了多小波的重要性质,对几个常用多小波作了预处理;图像压缩应用实验结果表明平衡处理比预滤波效果好,尤其是Opt-recl多小波能精确重构,无边界失真,在一定的压缩比下可达到很高的峰值信噪比PSNR. 相似文献
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基于遗传算法的多小波自适应去噪方法研究 总被引:1,自引:0,他引:1
针对噪声在多小波分解后的尺度性以及图像本身的特性,提出了一种基于遗传算法的多小波自适应去噪算法,该方法能通过遗传算法自适应地寻求去噪后图像的最小均方误差.实验结果表明,该算法优于传统算法,不仅能有效滤除图像的噪声,而且能较好地保留图像的边缘信息,具有更加理想的去噪效果. 相似文献
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Translation-invariant denoising using multiwavelets 总被引:9,自引:0,他引:9
Translation invariant (TI) single wavelet denoising was developed by Coifman and Donoho (1994), and they show that TI is better than non-TI single wavelet denoising. On the other other hand, Strela et al. (1994) have found that non-TI multiwavelet denoising gives better results than non-TI single wavelets. We extend Coifman and Donoho's TI single wavelet denoising scheme to multiwavelets. Experimental results show that TI multiwavelet denoising is better than the single case for soft thresholding 相似文献
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Introduction Infrared Image denoising is a basic problem of image processing.It is well known that the more prioriknowledge is used,the better filtering effect is gotten.Usually,we can only get a contaminated image and prioriknowledge of noise can not be gotten accurately so the filtering effect is not good.Wavelet denoising algorithmproposed by Donoho et al.[1]is widely used.It is considered the better denoising algorithm recently.However,itrequires size of image to determine the important … 相似文献
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对含脉冲噪声的图像去噪算法的研究 总被引:1,自引:0,他引:1
在传统均值滤波和中值滤波的基础上,结合聚类算法理论,采用硬聚类算法和模糊模型两种算法消除图像中的脉冲噪声。与传统的滤波算法和硬聚类模型去噪算法相比,基于模糊模型的去噪算法更好地提高了图像的清晰度和信噪比。 相似文献
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Ahmed OA 《IEEE transactions on medical imaging》2005,24(6):809-816
A new scheme for denoising magnetic resonance spectroscopy (MRS) signals is presented. This scheme is based on projecting noisy MRS signals in different domains, consecutively, and performing noise filtering operations in these domains. The domains are chosen such that the noise portion, which is inseparable from the desired signal in one domain, is separable in the other. A set of stable, linear, time-frequency (SLTF) transforms with different resolutions was selected for these projections as an example. Scheme evaluation was performed using extensive MRS signals with various noise levels. Compared with one domain denoising, it was observed that the proposed scheme gives superior results that compensate for the excess computational requirements. The proposed scheme supersedes also the wavelet packet denoising schemes. 相似文献
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Optimizing the multiwavelet shrinkage denoising 总被引:3,自引:0,他引:3
Denoising methods based on wavelet domain thresholding or shrinkage have been found to be effective. Recent studies reveal that multivariate shrinkage on multiwavelet transform coefficients further improves the traditional wavelet methods. It is because multiwavelet transform, with appropriate initialization, provides better representation of signals so that their difference from noise can be clearly identified. We consider the multiwavelet denoising by using multivariate shrinkage function. We first suggest a simple second-order orthogonal prefilter design method for applying multiwavelet of higher multiplicities. We then study the corresponding thresholds selection using Stein's unbiased risk estimator (SURE) for each resolution level provided that we know the noise structure. Simulation results show that higher multiplicity wavelets usually give better denoising results and the proposed threshold estimator suggests good indication for optimal thresholds. 相似文献
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M带小波变换是标准二带小波变换的自然推广,能够分析具有相对窄带的高频信号,而且能更好的集中信号能量,因此在信号处理中应用广泛。本文结合模糊聚类算法,提出了一种新的基于M带小波变换的图像去噪算法,利用模糊聚类算法把小波系数划分成两类:包含信号的小波系数与只包含噪声的小波系数,对只包含噪声的小波系数置为零,将包含信号的小波系数进行利用软阈值法进行收缩,最后对处理后的系数进行M带小波逆变换,得到去噪后的图像。对SAR图像的实验结果表明,该算法有效,而且能较好地保留边缘信息。 相似文献
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基于平稳多小波变换的红外图像噪声抑制方法 总被引:10,自引:3,他引:7
提出了一种平稳多小波变换方法,该方法结合多小波和平稳小波变换在信号去噪方面的优点,给出了二维图像平稳多小波变换的mallat分解重构算法,并对红外图像的平稳多小波变换系数进行阚值处理实现图像去噪,仿真结果表明,相对于平稳标量小波变换和多小波的噪声抑制方法,此方法对噪声有更好的抑制作用,并尽可能多的保持目标的特征和细节. 相似文献
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Simultaneous Speckle Reduction and SAR Image Compression Using Multiwavelet Transform 总被引:1,自引:0,他引:1
Ai-Li Wang Ye Zhang Yan-Feng Gu 《中国电子科技》2007,5(2):163-166
Synthetic aperture radar (SAR) images are corrupted by multiplicative speckle noise which limits the performance of the classical coder/decoder algorithm in spatial domain. The relatively new transform of multiwavelets can possess desirable features simultaneously, such as orthogonality and symmetry, while scalar wavelets cannot. In this paper we propose a compression scheme combining with speckle noise reduction within the multiwavelet framework. Compared with classical set partitioning in hierarchical trees (SPIHT) algorithm, our method achieves favorable peak signal to noise ratio (PSNR) and superior speckle noise reduction performances. 相似文献
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