Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: Wiener's filters.
Dissertationen zum Thema „Wiener's filters“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Dissertationen für die Forschung zum Thema "Wiener's filters" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Dissertationen für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Petrásek, Daniel. „Zpracování termálních obrazů technikou superresolution“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220622.
Der volle Inhalt der QuelleAnnotation:
Thesis deals with problematic of raising digital image spacial resolution, mainly thermal image. There are mentioned methods of interpolation, panorama and super-resolution. Main topic of this thesis is super-resolution which is detailly described during the thesis. Finally there is a description of algorithm implementation and problems that may occur during the implemetation.
2
Zamazal, Zdeněk. „Číslicové zpracování signálů v reálném čase“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219215.
Der volle Inhalt der QuelleAnnotation:
This work deals with digital signal processing in the field of adaptive filtering. Fundamental basics of adaptive filtering are described and primary aim is to create executable laboratory examples, using adaptive filtering, in LabView programming language. These laboratory examples are intended to be used by students fo studying and during laboratory lessons. Objective is to connect the examples with external devices, such as microphone. A microphone is used as an user's speech input acquiring interface. In the thesis is depicted Wiener's filter and problem of adaptive filtering is discussed. Contemporary adaptive algorithms are described and their applications as well. Most mentioned is the LMS algorithm and it's forms. Laboratory examples use following concepts: Adaptive Echo Cancellation, Active Noise Control and System Identification. Each of these examples is solely executable (need for LabView or Run-time engine), consisting also of theory with diagrams. Examples therefore are usable even without manual.
3
Jalůvková, Lenka. „Eliminace zkreslení obrazů duhovky“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220862.
Der volle Inhalt der QuelleAnnotation:
This master`s thesis is focused on a suppression of a distorsion in iris images. The aim of this work is to study and describe existing degradation methods (1D motion blur, uniform 2D motion blur, Gaussian blur, atmospheric turbulence blur, and out of focus blur). Furthermore, these methods are implemented and tested on a set of images. Then, we designed methods for suppression of these distorsions - inverse filtration, Wiener filtration and iterative deconvolution. All of these methods were tested and evaluated. Based on the experimental results, we can conclude that the Wiener-filter restoration is the most accurate approach from our test set. It achieves the best results in both normal and iterative mode.
4
Nakashima, Giovana Yuko. „Aplicação do filtro de WIENER para tratamento de sinais eletromiográficos“. Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-11122003-151819/.
Der volle Inhalt der QuelleAnnotation:
A eletromiografia consiste no estudo do movimentos dos músculos através dos sinais elétricos emitidos pelos mesmos. Esses sinais são captados por meio de eletrodos (de surpefície ou de agulha), sendo muito suscetíveis a variações e interferências não relacionadas diretamente com o movimento muscular (ruídos). Visando obter dados qualitativamente confiáveis, o processamento digital de sinais fornece como ferramentas os filtros ótimos e adaptativos, que são utilizados quando o sinal desajado está contaminado por ruído. Com a finalidade de diminuir o ruído presente no sinal eletromiográfico, foram implementados os filtros de wiener e wiener adaptativo ao algoritmo LMS (least mean square), tendo a análise da relação sinal/ruído dos sinais obtidos demonstrado que não há diferença significativa entre os filtros. Como conclusão, no tratamento de sinais eletromiográficos, pode-se aplicar tanto o filtro de wiener como o de wiener adaptativo, observando-se que este último apresenta a vantagem de consumir menos tempo de processamento.Electromyography is the study of muscle moviments through the electrical signal that they emanate. These signals are detected with eletrodes (surface or needle), where variations and interferences not directly related with movement are present (noises). Digital signal processing provides optimal and adaptative filters with the aim to get qualitative reliable data. The filters are used when desired signal is corrupted by noise. With the purpose of noise reduction in electromyography signal, wiener and adaptative wiener filters (the last one with least mean square algorithm) were implemented. However, signal-to-noise ratio analysis gave evidence that there is no significative difference between both the filters. As conclusion, in electromygraphy signal treatment, wiener and adaptative wiener filters could be used, with the only difference that the last one takes less processing time.
5
Hiemstra, John David. „Robust Implementations of the Multistage Wiener Filter“. Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/26714.
Der volle Inhalt der QuelleAnnotation:
The research in this dissertation addresses reduced rank adaptive signal processing, with specific emphasis on the multistage Wiener filter (MWF). The MWF is a generalization of the classical Wiener filter that performs a stage-by-stage decomposition based on orthogonal projections. Truncation of this decomposition produces a reduced rank filter with many benefits, for example, improved performance.
This dissertation extends knowledge of the MWF in four areas. The first area is rank and sample support compression. This dissertation examines, under a wide variety of conditions, the size of the adaptive subspace required by the MWF (i.e., the rank) as well as the required number of training samples. Comparisons are made with other algorithms such as the eigenvector-based principal components algorithm. The second area investigated in this dissertation concerns â soft stopsâ , i.e., the insertion of diagonal loading into the MWF. Several methods for inserting loading into the MWF are described, as well as methods for choosing the amount of loading. The next area investigated is MWF rank selection. The MWF will outperform the classical Wiener filter when the rank is properly chosen. This dissertation presents six approaches for selecting MWF rank. The algorithms are compared to one another and an overall design space taxonomy is presented. Finally, as digital modelling capabilities become more sophisticated there is emerging interest in augmenting adaptive processing algorithms to incorporate prior knowledge. This dissertation presents two methods for augmenting the MWF, one based on linear constraints and a second based on non-zero weight vector initialization. Both approaches are evaluated under ideal and perturbed conditions.
Together the research described in this dissertation increases the utility and robustness of the multistage Wiener filter. The analysis is presented in the context of adaptive array processing, both spatial array processing and space-time adaptive processing for airborne radar. The results, however, are applicable across the entire spectrum of adaptive signal processing applications.Ph. D.
6
Kayrish, Matthew Greco. „Robust GM Wiener Filter in the Complex Domain“. Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/19230.
Der volle Inhalt der QuelleAnnotation:
Space-Time Adaptive Processing is a signal processing technique that uses an adaptive array to help remove nonhomogeneous data points from a dataset. Since the early 1970s, STAP has been used in radar systems for their ability to "filter clutter, interference and jamming signals. One major flaw with early STAP radar systems is the reliance on non-robust estimators to estimate the noise condition. When even a single outlier is present, the earliest STAP radar systems would break down, causing the target to be missed. Many algorithms have been developed to successfully estimate the noise condition of the dataset when outliers are present. As recently as 2007, a STAP radar processing system based on Adaptive Complex Projection Statistics has been proposed and successfully"filters out the noise condition even when outliers are present. However, this algorithm requires the data to be entirely real. Radar data, which consists of amplitude and phase, is complex valued. Therefore, it must be converted into its rectangular components before processing can commence. This introduces many additional processing steps which significantly increase the computing time. The STAP radar algorithm of this thesis overcomes the problems with early radar systems. It is based on the Complex GM Wiener Filter (CGMWF) with the Minimum Covariance Determinant (MCD) for outlier detection. The robustness of the conventional Wiener "lter is enhanced by robust Huber Estimator, and using the MCD enables processing entirely in the complex domain. This results in a STAP radar algorithm with a breakdown point of nearly 35% and that enables processing entirely in the complex domain for fewer computing steps.Master of Science
7
Wang, Jingbo. „Multi-channel Wiener filters and their application to seismic array data“. Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608809.
Der volle Inhalt der Quelle
8
Tan, Sovira. „A pattern recognition Wiener filter for realistic clutter backgrounds“. Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390826.
Der volle Inhalt der Quelle
9
Bowman, Kevin W. „Application of wavelets to adaptive optics and multiresolution wiener filtering“. Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/14920.
Der volle Inhalt der Quelle
10
Warner, Carl Michael 1952. „ESTIMATION OF NONSTATIONARY SIGNALS IN NOISE (PROCESSING, ADAPTIVE, WIENER FILTERS, ESTIMATION, DIGITAL)“. Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291297.
Der volle Inhalt der Quelle
11
Barnes, Leighton P. (Leighton Pate). „Uniform FIR approximation of causal Wiener filters with applications to causal coherence“. Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100295.
Der volle Inhalt der QuelleAnnotation:
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 35-36).
Leveraging the relationship between Wiener filtering and the coherence function, a version of coherence is defined that captures the causal relationship between WSS processes. This causal coherence is interpreted in a modeling context and used to demonstrate what a frequency dependent measure for causality both can and can't represent. To understand how well frequency dependent coherence spectra can be estimated with finite order approximations, the convergence of the FIR causal Wiener lters to the full IIR causal Wiener filter is investigated as filter length goes to infinity. The main results prove Lp convergence of the frequency responses for p = 1, 2, [infinity] under certain Hölder continuity conditions on the power spectra, as well as give asymptotic upper bounds for the convergence error. Keywords: Wiener lters, causality, coherence, FIR approximation
by Leighton P. Barnes.
M. Eng.
12
Burada, Ranga. „Joint Resampling and Restoration of Hexagonally Sampled Images Using Adaptive Wiener Filter“. University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1450415906.
Der volle Inhalt der Quelle
13
Kim, Sang-Myeong. „Active control of sound in structural-acoustic coupled systems“. Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245303.
Der volle Inhalt der Quelle
14
Smital, Lukáš. „Vlnková filtrace elektrokardiogramů“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-233607.
Der volle Inhalt der QuelleAnnotation:
This dissertation deals with possibilities of using wavelet transforms for elimination of broadband muscle noise in ECG signals. In this work, the characteristics of ECG signals and particularly the most frequently occurring type of interference are discussed firstly. The theory of wavelet transforms is also introduced and followed by design of the simple wavelet filter and the more sophisticated version with wiener filtering of wavelet coefficients. Next part is devoted to the design of our filter, which is based on wavelet wiener filtering and is complemented by algorithms that ensure full adaptability of its parameters when the properties of the input signal are changing. Suitable parameters of the proposed system are searched automatically and the algorithm is tested on the complete standard electrocardiograms database CSE, where it achieves significantly better results than other published methods.
15
Jeanvoine, Arnaud. „Intérêt des algorithmes de réduction de bruit dans l’implant cochléaire : Application à la binauralité“. Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10338/document.
Der volle Inhalt der QuelleAnnotation:
Les implants cochléaires sont des appareils destinés à la réhabilitationdes surdités profondes et totales. Ils assurent la stimulation du nerf auditif en plaçant des électrodes dans la cochlée. Différentes études ont été établis afin d’améliorer l’intelligibilité de la parole dans le bruit chez le patientporteur de cet appareil. Les techniques bilatérales et binaurales permettent dereproduire une audition binaurale, car les deux oreilles sont simulées (commepour les personnes normo-entendantes). Ainsi la localisation et la perceptiondes sons environnants sont améliorées par rapport à une implantationmonaurale. Toutefois, les capacit´es de reconnaissances des mots sont trèsvite limitées en pr´esence de bruits. Nous avons d´evelopp´es des techniquesde r´eduction de bruit afin d’augmenter les performances de reconnaissance.Des améliorations de 10% à 15% suivant les conditions ont été observées. Néanmoins, si la perception est améliorée par les algorithmes, ils focalisent sur une direction, et ainsi, la localisation est alors réduite à l’angle delocalisation. Une seconde étude a alors été effectuée pour mesurer l’effetdes algorithmes sur la localisation. Ainsi, le beamformer donne les meilleurs résultats de compréhension mais la moins bonne localisation. La ré-injectiond’un pourcentage du signal d’entrée sur la sortie a permis de compenser laperte de la localisation sans détériorer l’intelligibilité. Le résultat de ces deux expériences montre qu’il faut un compromis entre laperception et la localisation des sons pour obtenir les meilleures performancesCochlear implants are to sail for the rehabilitation of deep and totaldeafness. They provide stimulation of the auditory nerve by placing electrodesin the cochlea. Various studies have been established to improve thespeech intelligibility in noise in the patient of this device. Bilateral andbinaural techniques allow reproducing a binaural hearing, since both earsare simulated (as for normal hearing people). Thus localization and theperception of the surrounding sounds are improved from a monauralimplantation. However, the recognition of the words capabilities are limitedvery quickly in the presence of noise.We developed noise reduction techniquesto increase the performance of recognition. Improvements of 10% to 15%depending on the conditions were observed. Nevertheless, if the perception isenhanced by algorithms, they focus on a direction, and thus the location isthen reduced at the corner of localization. Then, a second study was madeto measure the effect of localization algorithms. Thus, the beamformer givesthe best results of understanding but the less good location. The re-injectionof a percentage of the input to the output signal helped offset the loss of thelocation without damaging the intelligibility.The result of these two experiments shows that it takes a compromisebetween perception and sound localization for best performance
16
Vieira, Marcelo Andrade da Costa. „Metodologia baseada nas funções de transferência para pré-processamento de imagens mamográficas digitais e sua aplicação em esquema computacional de auxílio ao diagnóstico“. Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-19112007-144354/.
Der volle Inhalt der QuelleAnnotation:
Este trabalho tem por objetivo a investigação do comportamento de equipamentos de radiodiagnóstico em termos da qualidade da imagem produzida e a subseqüente aplicação desses resultados na otimização do desempenho de esquemas computacionais de auxílio ao diagnóstico, também conhecidos como esquemas CAD (do inglês, Computer-Aided Diagnosis). A principal meta consiste no desenvolvimento de técnicas de pré-processamento para imagens mamográficas digitalizadas que as realçasse de acordo com as características e limitações dos equipamentos utilizados na sua aquisição. A proposta está dividida em duas etapas. Na primeira, foram determinadas as características relativas tanto à resolução espacial como à resolução de contraste de diversos equipamentos mamográficos, avaliadas respectivamente pelas funções de transferência óptica e espectros de Wiener do ruído. Isto permitiu, numa segunda etapa, o desenvolvimento de um filtro digital específico para o pré-processamento de diferentes conjuntos de mamogramas digitais, separados de acordo com os equipamentos utilizados no processo de aquisição. Dessa forma, cada imagem mamográfica teve sua qualidade melhorada de acordo com as características do equipamento que a gerou, determinadas na primeira etapa. Essas imagens, depois de realçadas, foram utilizadas em um esquema CAD previamente desenvolvido, onde pôde ser observada uma melhora em até 12% no seu desempenho quando comparado aos resultados obtidos com imagens mamográficas não realçadas.The purpose of this work is to evaluate the quality of radiological equipment and their images in order to use these evaluations to improve the performance of a computer-aided diagnosis (CAD) scheme. The mean idea is about the development of image processing techniques to enhance digital mammograms according to the characteristics of the X-ray unit used for image acquisition. This work is basically divided in two parts. In the first one, it were determined the characteristics related to spatial and contrast resolution of several mammographic equipment, evaluated respectively from the optical transfer function and noise Wiener spectrum. This evaluation allowed, in a second part, the development of a preprocessing technique to enhance different set of digital mammographic images, gathered according to the equipment used on its acquisition process. Thus, each mammographic image had its quality improved in conformity with the characteristics of the equipment used on its acquisition, determined in the first part of this work. These images, after the enhancement process, were used on a previously developed CAD scheme. It was observed an improvement of 12% on the CAD performance using pre-processed mammograms compared to the results obtained when using non-enhanced mammographic images.
17
Ruiz, Fontes Natanael. „An analysis of the IIR an FIR Wiener filters with applications to underwater acoustics“. Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333441.
Der volle Inhalt der QuelleAnnotation:
Thesis (M.S. in Engineering Acoustics and M.S. in Electrical Engineering) Naval Postgraduate School, June 1997.Thesis advisor, Charles W. Therrien. Includes bibliographical references (p. 75). Also available online.
18
Moldříková, Zuzana. „Metody potlačení šumu pro rozpoznávače řeči“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220874.
Der volle Inhalt der QuelleAnnotation:
This diploma thesis deals with methods of noise suppression for speech recognition systems. In theoretical part are discussed basic terms of this topic and also methods for noise suppression. These are spectral subtraction, Wiener filtering, RASTA, mapping of spectrogram or algorithms based on noise estimation. In second part types of noise are analyzed, there is proposal and implementation of spectral subtraction method of noise suppression for speech recognition system. Also extensive testing of spectral subtractive algorithms in comparison with Wiener filter is conducted. Assessment of this testing is done with defined metrics, successfulness of recognition, recognition system score and signal to noise ratio.
19
Zobačová, Barbora. „Segmentace signálů EKG na základě jejich kvality“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377765.
Der volle Inhalt der QuelleAnnotation:
This semestral thesis deals with methods for continuous estimation of the quality of the ECG signal. The theoretical part includes the functional anatomy of the heart, the basics of electrocardiography, the types of noise that can be found in the ECG records, and a description of several methods for the continuous estimation of the ECG signal quality. Next here are some approaches to segmenting ECG signals based on their quality. The practical part deals with the implementation of two methods. The first method is the SNR estimation method based on the Wiener filter. The second method is the method of segmentation of ECG signals based on their quality. Both methods were tested on artificial and real signals.
20
Janů, Joshua. „Vlnkový wienerovský filtr EKG signálů“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220872.
Der volle Inhalt der QuelleAnnotation:
The thesis focuses on the use of wavelet wiener filtration to remove muscular interference from ECG signals. As part of it, a filter has been implemented in the MATLAB programming environment. The main part of the thesis deals with the optimization of numerical parameters of the proposed filter. The results of the filtration are compared with the results reported by other authors.
21
Mohamed, Khaled Mohamed Ahmied. „A Collaborative Adaptive Wiener Filter for Image Restoration and Multi-frame Super-resolution“. University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1426536832.
Der volle Inhalt der Quelle
22
ALVES, Fábio José da Costa. „Avaliação do efeito de janela e descoloração nos filtros Wiener-Hopf“. Universidade Federal do Pará, 1999. http://repositorio.ufpa.br/jspui/handle/2011/5677.
Der volle Inhalt der QuelleAnnotation:
Submitted by Cleide Dantas (cleidedantas@ufpa.br) on 2014-06-11T12:34:33Z
No. of bitstreams: 2
license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5)
Dissertacao_AvaliacaoEfeitoJanela.pdf: 12983544 bytes, checksum: d8af62d9b160f107ec5594c633121e76 (MD5)Rejected by Irvana Coutinho (irvana@ufpa.br), reason: Indexar os assuntos on 2014-08-07T16:24:38Z (GMT)
Submitted by Cleide Dantas (cleidedantas@ufpa.br) on 2014-09-04T13:08:03Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoEfeitoJanela.pdf: 12983544 bytes, checksum: d8af62d9b160f107ec5594c633121e76 (MD5)
Approved for entry into archive by Irvana Coutinho (irvana@ufpa.br) on 2014-09-10T16:37:25Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoEfeitoJanela.pdf: 12983544 bytes, checksum: d8af62d9b160f107ec5594c633121e76 (MD5)
Made available in DSpace on 2014-09-10T16:37:25Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoEfeitoJanela.pdf: 12983544 bytes, checksum: d8af62d9b160f107ec5594c633121e76 (MD5) Previous issue date: 1999
A presente dissertação consta de estudos sobre deconvolução sísmica, onde buscamos otimizar desempenhos na operação de suavização, na resolução da estimativa da distribuição dos coeficientes de reflexão e na recuperação do pulso-fonte. Os filtros estudados são monocanais, e as formulações consideram o sismograma como o resultado de um processo estocástico estacionário, e onde demonstramos os efeitos de janelas e de descoloração. O principio aplicado é o da minimização da variância dos desvios entre o valor obtido e o desejado, resultando no sistema de equações normais Wiener-Hopf cuja solução é o vetor dos coeficientes do filtro para ser aplicado numa convolução. O filtro de deconvolução ao impulso é desenhado considerando a distribuição dos coeficientes de reflexão como uma série branca. O operador comprime bem os eventos sísmicos a impulsos, e o seu inverso é uma boa aproximação do pulso-fonte. O janelamento e a descoloração melhoram o resultado deste filtro. O filtro de deconvolução aos impulsos é desenhado utilizando a distribuição dos coeficientes de reflexão. As propriedades estatísticas da distribuição dos coeficientes de reflexão tem efeito no operador e em seu desempenho. Janela na autocorrelação degrada a saída, e a melhora é obtida quando ela é aplicada no operador deconvolucional. A transformada de Hilbert não segue o princípio dos mínimos-quadrados, e produz bons resultados na recuperação do pulso-fonte sob a premissa de fase-mínima. O inverso do pulso-fonte recuperado comprime bem os eventos sísmicos a impulsos. Quando o traço contém ruído aditivo, os resultados obtidos com auxilio da transformada de Hilbert são melhores do que os obtidos com o filtro de deconvolução ao impulso. O filtro de suavização suprime ruído presente no traço sísmico em função da magnitude do parâmetro de descoloração utilizado. A utilização dos traços suavizados melhora o desempenho da deconvolução ao impulso. A descoloração dupla gera melhores resultados do que a descoloração simples. O filtro casado é obtido através da maximização de uma função sinal/ruído. Os resultados obtidos na estimativa da distribuição dos coeficientes de reflexão com o filtro casado possuem melhor resolução do que o filtro de suavização.
The present masters dissertation consists of studies on seismic deconvolution where we look for otimizing the operations of smoothing, of resolution for the estimation of distribution of reflection coefficients, and of recovery of source-pulse. The studied filters are single channel, and the formulations consider the seismic trace as the result of a stationary stochastic process, and we demonstrate the effects of taper windows and of prewhitening in resolution. The applied principle is the minimization of the difference's variance between real and desired outputs, resulting on a system Wiener-Hopf normal equations whose solution is the vector of filter coefficients to be applied in a convolution. Spike deconvolution is designed considering the distribution of reflection coefficients as a white series. The operator compresses the seismic events to impulses, and its inverse is a good approximation to the source-pulse. The application of taper windows and of prewhitening improve the output of this filter. Spike-series filters are designed using the distribution of reflection coefficients. The statistical properties of the reflection coefficients distribution affect the operator and its performance. Taper windows on autocorrelation degrades the output, and improvement is achieved when it is applied to the deconvolutional operator. The Hilbert transform produces good results in the recovery of source-pulse, under the premise of minimum-phase. The inverse of the recovered source-pulse compresses the seismic events to impulses. When the seismic trace contains additive noise, the results obtained with Hilbert transform are better than with spike deconvolution. Smoothing filter suppresses noise in the seismic trace as a function of a prewhitening parameter. The use of smoothed traces improves the spike deconvolution. Double prewhitening generates better results than the simple prewhitening. The matched filter operator is obtained from maximization of a signal/noise ratio function. Deconvolving the output of the matched filter for the estimation of the distribution of reflection coefficients possess better resolution than when using a smoothing filter.
23
Rucci, Michael. „Computationally Efficient Video Restoration for Nyquist Sampled Imaging Sensors Combining an Affine-Motion Based Temporal Kalman Filter and Adaptive Wiener Filter“. University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398286798.
Der volle Inhalt der Quelle
24
SMITH, WARREN ESCHHOLZ. „SIMULATED ANNEALING AND ESTIMATION THEORY IN CODED-APERTURE IMAGING (RECONSTRUCTION, MONTE CARLO, WIENER FILTER)“. Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188135.
Der volle Inhalt der QuelleAnnotation:
Coded-aperture imaging without detector motion can be used to reconstruct three-dimensional radionuclide distributions in the context of nuclear medicine. This approach offers several advantages over the rotating gamma-ray camera systems presently employed in the clinic. These advantages include improved sensitivity, potentially better spatial resolution, and the capability of doing dynamic studies. There are two problems associated with the coded-aperture approach, however. First, the data is "multiplexed", which refers to the fact that many line integrals of the source distribution are combined together and not measured individually, so that information is lost. Second, the number of resolvable detector elements is typically an order of magnitude less than the number of object elements to be reconstructed, so that the reconstruction problem is underdetermined. Consequently, the reconstruction is not unique. By using various types of a priori information in forming the reconstruction, however, it is possible to augment the incomplete data set. Two algorithms are presented to reconstruct objects from their coded-image projections and various types of a priori information. The first, a Monte Carlo algorithm, is a flexible and computationally efficient approach using the a priori knowledge of positivity and nearest-neighbor correlation. This algorithm is used to qualitatively explore the effect of the data-taking geometry on reconstruction performance. The second algorithm is a linear estimator incorporating as a priori knowledge completely general first- and second-order statistical information about the object class to be reconstructed. The linear-estimator formalism also provides a minimum-variance expression for system optimization. This linear algorithm is used to explore the effects of correct and incorrect a priori information on reconstruction performance, and to quantitatively investigate reconstruction quality with respect to data-taking geometry.
25
Zhou, Zheng N. „Space-time adaptive processing with multi-staged Wiener filter and principal component signal dependent algorithms“. DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/276.
Der volle Inhalt der QuelleAnnotation:
Space-time Adaptive Processing (STAP) is a two-dimensional filtering technique for antenna array with multiple spatial channels. The name "space-time" describes the coupling of these spatial channels with pulse-Doppler waveforms. Applications for STAP includes ground moving target indicator (GMTI) for airborne radar systems.
Today, there are strong interests to develop STAP algorithms for operations in “sample starved” environments, where intense environmental interference can reduce STAP capacity to detect and track ground targets. Careful applications of STAP can effectively overcome these conditions by suppressing these interferences and maximize the signal to interference plus noise ratio (SINR). The Multi-stage Wiener filter (MWF) and principal component signal dependent (PC-SD) algorithm are two such methods that can suppress these interference through truncation of the signal subspace.
This thesis makes contribution in several ways. First it details the importance of rank compression and sample compression for effective STAP operations in “sample starved” environments. Second, it shows how MWF and PC-SD could operate in this type of environment. Third it details how a “soft stop” technique like diagonal loading (DL) could improve STAP performance in target detection for MWF and PC-SD. Fourth, this thesis contrasts the performance of several existing “hard stop” techniques in rank compression and introduces a new one using a-priori knowledge.
26
Romualdo, Larissa Cristina dos Santos. „Restauração de imagens mamográficas digitais utilizando o filtro de Wiener no domínio de Anscombe e o filtro inverso da MTF no domínio da frequência“. Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18152/tde-17112009-084935/.
Der volle Inhalt der QuelleAnnotation:
Este trabalho tem por objetivo o desenvolvimento de uma nova técnica de pré-processamento de imagens mamográficas digitais para melhorar o desempenho dos esquemas computacionais de auxílio ao diagnóstico (CAD) e para auxiliar na detecção precoce do câncer de mama. O método proposto efetua uma restauração nas imagens mamográficas utilizando, em uma primeira etapa, a transformada de Anscombe e o filtro de Wiener para redução do ruído quântico. Posteriormente, é utilizado o filtro inverso da função de transferência de modulação (MTF) do sistema de imagem para realce das estruturas de interesse na mamografia, como as microcalcificações, que podem ser um indicativo de câncer de mama em seu estágio inicial. Imagens mamográficas restauradas pelo método proposto foram utilizadas na avaliação de um esquema CAD para detecção automática de microcalcificações. Os resultados mostraram que o desempenho do esquema CAD apresentou uma melhora significativa quando imagens restauradas foram utilizadas, mesmo para imagens de mamas densas, que resultam normalmente em baixa taxa de detecção devido ao baixo contraste.This work aims to developing a new technique for pre-processing digital mammographic images in order to improve the performance of computer aided-diagnosis schemes (CAD) and to assist in early detection of breast cancer. The proposed method performs a restoration in mammographic images using in a first step, the Anscombe transform and Wiener filtering to reduce image quantum noise. Subsequently, it was used the inverse modulation transfer function filtering (MTF) considering the imaging system to enhance structures of interest in mammography, such as microcalcifications, which may be an indicative of breast cancer in its early stage. Mammographic images restored by the proposed method were used in the evaluation of a CAD scheme for automatic detection of microcalcifications. The results showed that the performance of the CAD scheme had a significant improvement when restored images were used, even for images of dense breasts, which often results in low detection rate due to low contrast.
27
Wiltgen, Timothy Edward. „Adaptive Beamforming using ICA for Target Identification in Noisy Environments“. Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33118.
Der volle Inhalt der QuelleAnnotation:
The blind source separation problem has received a great deal of attention in previous years. The aim of this problem is to estimate a set of original source signals from a set of linearly mixed signals through any number of signal processing techniques. While many methods exist that attempt to solve the blind source separation problem, a new technique is being used that uniquely separates audio sources as they are received from a microphone array. In this thesis a new algorithm is proposed that that utilizes the ICA algorithm in conjunction with a filtering technique that separates source signals and then removes sources of interference so that a signal of interest can be accurately tracked. Experimental results will compare a common blind source separation technique to the new algorithm and show that the new algorithm can detect a signal of interest and accurately track it as it moves through an anechoic environment.Master of Science
28
Juráček, Ivo. „Zabezpečení senzorů - ověření pravosti obrazu“. Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2020. http://www.nusl.cz/ntk/nusl-432921.
Der volle Inhalt der QuelleAnnotation:
Diploma thesis is about image sensor security. Goal of the thesis was study data integrity gained from the image sensors. Proposed method is about source camera identification from noise characteristics in image sensors. Research was about influence of denoising algorithms applied to digital images, which was acquired from 15 different image sensors. Finally the statistical evaluation had been done from computed results.
29
Escarpinati, Mauricio Cunha. „Desenvolvimento de um sistema computacional para utilização em procedimentos de controle de qualidade em equipamentos mamográficos“. Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-27082007-213453/.
Der volle Inhalt der QuelleAnnotation:
O presente trabalho consiste na elaboração de uma metodologia envolvendo técnicas computacionais para proporcionar informações provenientes de avaliação de qualidade de equipamentos mamográficos. A investigação conduzida levou em conta, além da necessária determinação de parâmetros operacionais - como tensão de pico (kVp), corrente de tubo, ponto focal, dose, tempo de exposição, camada semi-redutora -, a influência das características do digitalizador usado no processo de digitalização das imagens a ser avaliadas pelo esquema computacional, seja esse um sistema de aquisição digital direta ou indireta. Dessa forma, foi elaborado um protocolo de pré-processamento da imagem para compensar os efeitos do digitalizador antes da avaliação dos parâmetros de qualidade através dela. Simultaneamente ao desenvolvimento dos softwares necessários ao esquema, foi projetado e desenvolvido um simulador radiográfico para servir como instrumento para obtenção tanto das imagens a ser processadas pelo modelo computacional, como dos dados referentes aos parâmetros operacionais. O sistema foi desenvolvido tomando um mamógrafo calibrado e um instrumento de precisão como referências e testado em outros equipamentos mamográficos em operação em clínicas e hospitais. Os resultados foram consistentes com as análises comparativas utilizando as referências, o que podem fazer do sistema uma ferramenta útil na avaliação de qualidade em mamografia.The present work consists on developing a computational methodology to provide information regarding to mammographic equipment quality evaluation. This investigation have taken into account, beyond the required operational parameters, such as kVp, electrical current, focal point, dose, exposition time, half-value layer, the influence of the film digitizer utilized for digitization process on the images to be evaluated by the computational scheme, either this a system of direct or indirect digital acquisition. Like so, it was elaborated an image pre-processing protocol to compensate the digitization effect on digital image, before the evaluation of quality control parameters through itself. Simultaneously to the development of the necessary software to the system, a radiographic phantom was developed to be used for achievement of either the images to be processed by the computational model, as operational parameters data. The system was developed taking calibrated mammographic equipment and a precise measurement instrument as references, besides, it was tested in other mammographic equipment in operation on clinics and hospitals. Results had shown consistent with the comparative analyses using those references, which can turn this system a useful tool for evaluation of mammography quality.
30
Suyama, Ricardo. „Sobre o criterio do modulo constante para equalização não-supervisionada e suas relações com a teoria de Wiener“. [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259106.
Der volle Inhalt der QuelleAnnotation:
Orientador: João Marcos Travassos RomanoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-03T19:02:04Z (GMT). No. of bitstreams: 1 Suyama_Ricardo_M.pdf: 6998059 bytes, checksum: 23e291ea4a8d0221cb595a18650b4149 (MD5) Previous issue date: 2003
Mestrado
31
Ledesma, Dorian Caraballo. „Deconvolução de dados sísmicos de reflexão utilizando mudança de fase do filtro de WIENER-LEVINSON“. http://www.pggeofisica.ufba.br, 2012. http://www.pggeofisica.ufba.br.
Der volle Inhalt der QuelleAnnotation:
Submitted by Souza Tanajura Augusto (cast@ufba.br) on 2012-12-17T16:57:06Z
No. of bitstreams: 1
Ledesma.pdf: 11225315 bytes, checksum: 6afe5af6603df7177da616068fb63cf4 (MD5)Made available in DSpace on 2012-12-17T16:57:06Z (GMT). No. of bitstreams: 1 Ledesma.pdf: 11225315 bytes, checksum: 6afe5af6603df7177da616068fb63cf4 (MD5)
Laboratório de Geofísica de Exploração de Petr óleo, convenio Rede01- Rede de Risco Exploratório, CTPETRO/FINEP/Petrobras
Uma tarefa importante do processamento de dados sIsmicos é a deconvolução. Ela tem o objetivo de melhorar a resolucão temporal e a coerência espacial dos refetores presentes nas secõe sísmicas. O método de deconvolução de Wiener-Levinson (WL) é o método clássico. Neste método o filtro é causal, também denominado de filtro de fase mínima, e é obtido com o método dos mínimos quadrados, através da solução de um sistema de equações normais. Tal filtro não é eficaz na deconvolução de pulsos de fase mista uma vez que estes não admitem inversa causal. Consequentemente, se o pulso sísmico não é de fase mínima o filtro de WL não produz um bom resultado. Apesar disso ele é normalmente utilizado porque pode ser obtido de forma simples e rápida. Na presente tese mostramos que a deconvolução utilizando o filtro inversão de fase mista, obtido através de operadores all-pass, preserva a equivalência com o espectro de amplitude da deconvolução de WL, e pode extrair a informação de fase do filtro e também do pulso estimado. O novo procedimento utiliza operadores all-pass para mudar a fase do filtro de fase mínima de WL, ou o pulso a ele associado. Testamos duas abordagens para obtenção de filtros inversos ótimos. Na primeira, os operadores all-pass são formados a partir de raízes fictícias do pulso sísmico, distribuídas, no plano complexo, na forma de uma coroa exterior ao círrculo de raio unitário. Na segunda abordagem são utilizadas diretamente as raízes calculadas a partir do filtro de WL. Mostramos que as duas abordagens permitem a obtenção de filtros inversos para a deconvolução de pulsos de fase mista e podem serutilizadas com sucesso no processamento de dados sísmicos. Para solução do problema de otimização, na escolha do filtro inverso ótimo, utilizamos o algoritmo genético, e para quantificar o desempenho dos operadores all-pass e selecionar o filtro inverso ótimo utilizamos a norma varimax do traço deconvolvido. O método de deconvolução de fase mista obtido através de operadores all-pass, foi testado sobre dados sísmicos sintéticos e dados sísmicos reais, utilizando seções síssmicas 2D na Bacia do Jequitinhonha. O novo método pode ser implementado computacionalmente de forma relativamente simples e pode ser utilizado para melhorar a identificação dos eventos sísmicos refletidos e revelar em maior detalhe as feições sismo-estratigráficas e estruturais, de interesse para a exploração e o estudo de reservatórios de hidrocarbonetos.
Pós Graduação em Geofísica da UFBA
32
Musznicki, Piotr. „Identification des perturbations CEM conduites dans les convertisseurs statiques par la méthode du filtre de Wiener“. Phd thesis, Grenoble INPG, 2007. http://tel.archives-ouvertes.fr/tel-00400074.
Der volle Inhalt der QuelleAnnotation:
Le sujet concerne l'utilisation de techniques de traitement du signal assez classiques (filtrage de wiener) pour permettre de reconstituer les perturbations CEM conduites émises par un convertisseur d'électronique de puissance. Ce travail va dans le sens d'une meilleure compréhension des perturbations générées par ces systèmes complexes, et pourra déboucher sur une amélioration de ces convertisseurs, sur un plan des lois de commande et des modes de commutation notamment. La méthode est développée et validée sur une simple cellule de commutation (Boost), puis mise en œuvre sur un onduleur de tension commandé en PWM, PDM et finalement, utilisant la résonance
33
Ribeiro, Eduardo da Silva. „Novas propostas em filtragem de projeções tomográficas sob ruído Poisson“. Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/438.
Der volle Inhalt der QuelleAnnotation:
Made available in DSpace on 2016-06-02T19:05:43Z (GMT). No. of bitstreams: 1
3115.pdf: 5210903 bytes, checksum: d78cb316f1a90afa1f1d9e435752a5f6 (MD5)
Previous issue date: 2010-05-24Financiadora de Estudos e Projetos
In this dissertation we present techniques for filtering of tomographic projections with Poisson noise. For the filtering of the tomogram projections we use variations of three filtering techniques: Bayesian estimation, Wiener filtering and thresholding in Wavelet domain. We used ten MAP estimators, each estimator with a diferent probability density as prior information. An adaptive windowing was used to calculate the local estimates. A hypothesis test was used to select the best probability density to each projection. We used the Pointwise Wiener filter and FIR Wiener Filter, in both cases we used a adaptive scheme for the filtering. For thresholding in wavelet domain, we tested the performance of four families basis of wavelet functions and four techniques for obtaining thresholds. The experiments were done with the phantom of Shepp and Logan and five set of projections of phantoms captured by a CT scanner developed by CNPDIA-EMBRAPA. The image reconstruction was made with the parallel POCS algorithm. The evaluation of the filtering was made after reconstruction with the following criteria for measurement of error: ISNR, PSNR, SSIM and IDIV.
Nesta dissertação técnicas de filtragem de projeções tomográficas com ruído Poisson são apresentadas. Utilizamos variações de três técnicas de filtragem: estimação Bayesiana, filtragem de Wiener e limiarização no domínio Wavelet. Foram utilizados dez estimadores MAP, em cada uma densidade de probabilidade foi utilizada como informação a priori. Foi utilizado um janelamento adaptativo para o cálculo das estimativas locais e um teste de hipóteses para a escolha da melhor densidade de probabilidade que se adéqua a cada projeção. Utilizamos o filtro de Wiener na versão pontual e FIR, em ambos os casos utilizamos um esquema adaptativo durante a filtragem. Para a limiarização no domínio Wavelet, verificamos o desempenho de quatro famílias de funções Wavelet e quatro técnicas de obtenção de limiares. Os experimentos foram feitos com o phantom de Shepp e Logan e cinco conjunto de projeções de phantoms capturas por um minitomógrafo no CNPDIAEMBRAPA. A reconstrução da imagem feita com o algoritmo POCS paralelo. A avaliação da filtragem foi feita após a reconstrução com os seguintes crit_erios de medida de erro: ISNR, PSNR, IDIV e SSIM.
34
Kokaram, Anil Christopher. „Motion picture restoration“. Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/256798.
Der volle Inhalt der QuelleAnnotation:
This dissertation presents algorithms for restoring some of the major corruptions observed in archived film or video material. The two principal problems of impulsive distortion (Dirt and Sparkle or Blotches) and noise degradation are considered. There is also an algorithm for suppressing the inter-line jitter common in images decoded from noisy video signals. In the case of noise reduction and Blotch removal the thesis considers image sequences to be three dimensional signals involving evolution of features in time and space. This is necessary if any process presented is to show an improvement over standard two-dimensional techniques. It is important to recognize that consideration of image sequences must involve an appreciation of the problems incurred by the motion of objects in the scene. The most obvious implication is that due to motion, useful three dimensional processing does not necessarily proceed in a direction 'orthogonal' to the image frames. Therefore, attention is given to discussing motion estimation as it is used for image sequence processing. Some discussion is given to image sequence models and the 3D Autoregressive model is investigated. A multiresolution BM scheme is used for motion estimation throughout the major part of the thesis. Impulsive noise removal in image processing has been traditionally achieved by the use of median filter structures. A new three dimensional multilevel median structure is presented in this work with the additional use of a detector which limits the distortion caused by the filters . This technique is found to be extremely effective in practice and is an alternative to the traditional global median operation. The new median filter is shown to be superior to those previously presented with respect to the ability to reject the kind of distortion found in practice. A model based technique using the 3D AR model is also developed for detecting and removing Blotches. This technique achieves better fidelity at the expense of heavier computational load. Motion compensated 3D IIR and FIR Wiener filters are investigated with respect to their ability to reject noise in an image sequence. They are compared to several algorithms previously presented which are purely temporal in nature. The filters presented are found to be effective and compare favourably to the other algorithms. The 3D filtering process is superior to the purely temporal process as expected. The algorithm that is presented for suppressing inter-line jitter uses a 2D AR model to estimate and correct the relative displacements between the lines. The output image is much more satisfactory to the observer although in a severe case some drift of image features is to be expected. A suggestion for removing this drift is presented in the conclusions. There are several remaining problems in moving video. In particular, line scratches and picture shake/roll. Line scratches cannot be detected successfully by the detectors presented and so cannot be removed efficiently. Suppressing shake and roll involves compensating the entire frame for motion and there is a need to separate global from local motion. These difficulties provide ample opportunity for further research.
35
Handl, Marek. „Vlnková filtrace signálů EKG“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220046.
Der volle Inhalt der QuelleAnnotation:
The work deals with the wavelet transformation, focusing on wavelet transforms with discrete time (DTWT). The practical part is focused on the implementation of redundant packet DTWT and its use in the filtration of ECG signals. The main part of the work is to design wiener filter that uses redundant packet DTWT, designed to eliminate interference myopotentials of ECG signals. The actual solution is implemented in Matlab. Testing is performed on the library CSE using noise model myopotentials used to noising original signals. For optimum parameters designed filter is used the genetic algorithm (GA). The work is carried out comparing the proposed filter redundant packet DTWT a variant of redundant dyadic DTWT.
36
Riad, Rabia. „Tatouage robuste d’images imprimées“. Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2068/document.
Der volle Inhalt der QuelleAnnotation:
Le tatouage invisible d’images d’identité imprimées sur un support en plastique est un problème difficile qui intéresse le monde industriel. Dans cette étude, nous avons développé un algorithme de tatouage robuste aux diverses attaques présentes dans ce cas. Ces attaques sont liées aux processus d’impression/numérisation sur le support plastique ainsi qu’aux dégradations qu’une carte plastique peut rencontrer le long de sa durée de vie. La méthode de tatouage opère dans le domaine de Fourier car cette transformée présente des propriétés d’invariances aux attaques géométriques globales. Une méthode préventive consiste en un prétraitement de l’image originale avant le processus d’insertion qui réduit la variance du vecteur support de la marque. Une méthode corrective comporte deux contre-attaques corrigeant le flou et les variations colorimétriques. Pour une probabilité de fausse alarme de 10⁻⁴, nous avons obtenu une amélioration moyenne de 22% par rapport à la méthode de référence lorsque seule la méthode préventive est utilisée. La combinaison de la méthode préventive avec la méthode corrective correspond à un taux de détection supérieur à 99%. L’algorithme de détection prends moins de 1 seconde pour à une image de 512×512 pixels avec un ordinateur classique ce qui est compatible avec l’application industrielle viséeInvisible watermarking for ID images printed on plastic card support is a challenging problem that interests the industrial world. In this study, we developed a watermarking algorithm robust to various attacks present in this case. These attacks are mainly related to the print/scan process on the plastic support and the degradations that an ID card can encounter along its lifetime. The watermarking scheme operates in the Fourier domain as this transform has invariance properties against global geometrical transformations. A preventive method consists of pre-processing the host image before the embedding process that reduces the variance of the embeddable vector. A curative method comprises two counterattacks dealing with blurring and color variations. For a false alarm probability of 10⁻⁴, we obtained an average improvement of 22% over the reference method when only preventative method is used. The combination of the preventive and curative methods leads to a detection rate greater than 99%. The detection algorithm takes less than 1 second for a 512×512 image with a conventional computer, which is compatible with the industrial application in question
37
Novotný, Jiří. „Filtrace svalového rušení v EKG signálech“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221363.
Der volle Inhalt der QuelleAnnotation:
This master's thesis deals with the optimization of numerical coefficients of the Wiener filter for muscle noise filtering in ECG signals. The theoretical part deals with ECG signal characteristic and muscle interference. It also contains a summary of the wavelet transform, wavelet Wiener's filtration, methods for calculating of the threshold and thresholding. In the last theoretical part the characteristic optimization techniques, the exhausive search and Nelder-Mead simplex method are mentioned, which were implemented in the practical part of this thesis in MATLAB. The functional verification and Wiener's filter optimization were tested on the standard electrocardiograms database CSE. By using the methods of exhausive search, the initial estimate for the solution method Nelder-Mead was obtained. The optimization method Nelder-Mead gives better results in the orders of hundredths or tenths than the method of exhausive search. The practical part is finished by the comparison of results of implemented algorithm with optimum coefficients, implemented in this thesis, with the results of other methods for filtering muscle interference in ECG signals.
38
Cohen, Zachary Gideon. „Noise Reduction with Microphone Arrays for Speaker Identification“. DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/884.
Der volle Inhalt der QuelleAnnotation:
The presence of acoustic noise in audio recordings is an ongoing issue that plagues many applications. This ambient background noise is difficult to reduce due to its unpredictable nature. Many single channel noise reduction techniques exist but are limited in that they may distort the desired speech signal due to overlapping spectral content of the speech and noise. It is therefore of interest to investigate the use of multichannel noise reduction algorithms to further attenuate noise while attempting to preserve the speech signal of interest.
Specifically, this thesis looks to investigate the use of microphone arrays in conjunction with multichannel noise reduction algorithms to aid aiding in speaker identification. Recording a speaker in the presence of acoustic background noise ultimately limits the performance and confidence of speaker identification algorithms. In situations where it is impossible to control the noise environment where the speech sample is taken, noise reduction algorithms must be developed and applied to clean the speech signal in order to give speaker identification software a chance at a positive identification. Due to the limitations of single channel techniques, it is of interest to see if spatial information provided by microphone arrays can be exploited to aid in speaker identification.
This thesis provides an exploration of several time domain multichannel noise reduction techniques including delay sum beamforming, multi-channel Wiener filtering, and Spatial-Temporal Prediction filtering. Each algorithm is prototyped and filter performance is evaluated using various simulations and experiments. A three-dimensional noise model is developed to simulate and compare the performance of the above methods and experimental results of three data collections are presented and analyzed. The algorithms are compared and recommendations are given for the use of each technique. Finally, ideas for future work are discussed to improve performance and implementation of these multichannel algorithms. Possible applications for this technology include audio surveillance, identity verification, video chatting, conference calling and sound source localization.
39
Čišecký, Roman. „Metody pro odstranění šumu z digitálních obrazů“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219769.
Der volle Inhalt der QuelleAnnotation:
The master's thesis is concerned with digital image denoising methods. The theoretical part explains some elementary terms related to image processing, image noise, categorization of noise and quality determining criteria of denoising process. There are also particular denoising methods described, mentioning their advantages and disadvantages in this paper. The practical part deals with an implementation of the selected denoising methods in a Java, in the environment of application RapidMiner. In conclusion, the results obtained by different methods are compared.
40
Sedláčková, Eva. „Vlnkový wienerovský filtr EKG signálů“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220843.
Der volle Inhalt der QuelleAnnotation:
The aim of this work is introduction with method of filtering the ECG signals using wavelet transformation and use of this method for filtering of signal disturbed with myopotencials. The work deals with general properties and with genesis of ECG signals and describes ECG curve. Next part of work is focused on wavelet transformation, types of wavelet transformation and different methods calculation thresholds and thresholding. Design part of work is focused on design Wiener filter for remove myopotencials from ECG signals and finding optimal parameters of this filter using optimization algorithm. For optimization is used simplex method. Discovered optimal parameters are assessed on CSE and MIT-BIH Arrhythmia database and compared with results of other authors.
41
Souza, Cristiane Loesch de. „Análise da aplicação do filtro wiener ao tratamento de dados da radiação cósmica de fundo obtido pelo telescópio“. Instituto Nacional de Pesquisas Espaciais, 2004. http://urlib.net/sid.inpe.br/jeferson/2004/12.20.08.44.
Der volle Inhalt der QuelleAnnotation:
Este trabalho apresenta a implementação do filltro Wiener para remoção de um ruído proporcional ao inverso da freqüência (x 1/f) presente nos dados do experimento BEAST, estabelecendo uma comparação entre seu desempenho e o do filtro atualmente utilizado (Passa altas) na análise de dados. O ruído 1/f aumenta a potência total do sinal em baixas freqüências e é responsável pelo aparecimento de estruturas (stripes) nos mapas de flutuações de temperatura da Radiação Cósmica de Fundo em Microondas (RCFM). A filtragem Wiener é uma técnica que permite a restauração de sinais a partir da separação de diferentes componentes, baseada em suas freqüências espectrais. Ela é considerada um método otimizado (optimal filtering) no sentido de que minimiza o erro médio quadrático no processo de filtragem inversa e na suavização do ruído. A aplicação desta técnica à série temporal de dados da RCFM produzida pelo BEAST deve preservar o sinal cosmológico contido nos dados, minimizando a perda de informação. Após a aplicação dos filtros ao processo de limpeza e redução de dados, são produzidos mapas e, a partir destes, espectros de potência das flutuações de temperatura. Os espectros de potência foram estimados utilizando-se o método MASTER. Os mapas do BEAST, gerados com ambos os filtros, foram correlacionados com o mapa do satelite WMAP e os espectros do BEAST foram correlacionados com o espectro do satelite WMAP e com um espectro sintético gerado com o código CMBFAST. Embora não tenham sido encontradas correlações signicativas entre os mapas, os resultados mostram correlações de 65% entre os espectros brutos e 80% entre os espectros binados. Os resultados obtidos sugerem que a tecnica de filtragem Wiener apresenta desempenho equivalente ao da filtragem Passa Altas no tratamento de dados da RCFM obtidos pelo experimento BEAST.This work presents the implementation of a Wiener filter to remove a type of noise proportional to the inverse of the frequency (/ 1=f) from the BEAST experiment data, estabilishing a comparison between its perfomance and the one from the filter presently used (Highpass) in the data analysis. The 1=f noise increases the total power of the signal at low frequencies and is responsible for the production of artifacts (stripes) on Cosmic Microwave Background (CMB) temperature maps. The Wiener filtering is a technique that allows signal reconstruction by separating different components, based on their spectral frequencies. It is considered an optimal filter in the sense that it minimizes the mean square error on inverse filtering processes and on noise smoothing. The aplication of this technique to CMB time ordered datasets produced by BEAST must preserve the cosmological signal present in the data, minimizing the loss of information. After applying the filter in the cleaning and data reduction processes, maps of temperature fluctuation are produced. We use the maps to estimate the power spectrum of the temperature fluctuations, using the MASTER method. BEAST maps, produced using both the Wiener and the Highpass filters, were correlated to WMAP temperature map and the BEAST spectra were correlated to WMAP spectra and to a synthetic spectrum generated by the CMBFAST package. Although signicant correlations have not been found between the maps, the results show correlations of 65% between the raw spectra and 80% between the binned ones. The results suggest that the Wiener ltering performance is equivalent to the Highpass filtering in the CMB data analisys of the BEAST data.
42
Silva, Luiz Felipe da. „Redução de ruídos em sinais de voz utilizando uma função de ganhos adaptativa para o filtro de Wiener“. Florianópolis, SC, 2011. http://repositorio.ufsc.br/xmlui/handle/123456789/95988.
Der volle Inhalt der QuelleAnnotation:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.Made available in DSpace on 2012-10-26T07:46:25Z (GMT). No. of bitstreams: 1 301279.pdf: 1226847 bytes, checksum: 0cb0c2277bd8cd20a78359b2dd08d11a (MD5)
Muitas técnicas de redução de ruído, especialmente a filtragem de Wiener, sofrem com a introdução de ruído musical e distorção do sinal de voz em SNRs baixas devido às suas funções ganho rígidas. Neste trabalho propomos uma modificação do filtro de Wiener paramétrico para enfatizar as contribuições espectrais nas regiões do espectro que são importantes para inteligibilidade. Isto é feito definindo um parâmetro adaptativo que é uma função do pitch. Medidas objetivas e testes estatísticos são usados para avaliar a qualidade subjetiva e inteligibilidade do sinal de voz. Os resultados indicam que o algoritmo proposto resulta na melhora da inteligibilidade e redução do ruído musical do sinal de voz processado, comparado com o filtro de Wiener convencional.
Many existing speech enhancement techniques, especially Wiener filtering, suffer from introducing annoying musical noise and speech distortion in low SNR due to their rigid gain functions. In this work we propose a modification to the parametric Wiener filter that emphasizes the spectral contributions in spectral regions which are important for intelligibility. This is done by defining an adaptive parameter that is a function of the pitch. Objective measures and statistical tests are used to assess subjective speech quality and intelligibility. The results indicate that the proposed algorithm results in speech intelligibility improvement and in musical noise reduction, as compared to the conventional Wiener filter.
43
Pedone, M. (Matteo). „Algebraic methods for constructing blur-invariant operators and their applications“. Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526208770.
Der volle Inhalt der QuelleAnnotation:
Abstract Image acquisition devices are always subject to physical limitations that often manifest as distortions in the appearance of the captured image. The most common types of distortions can be divided into two categories: geometric and radiometric distortions. Examples of the latter ones are: changes in brightness, contrast, or illumination, sensor noise and blur. Since image blur can have many different causes, it is usually not convenient and also computationally expensive to develop ad hoc algorithms to correct each specific type of blur. Instead, it is often possible to extract a blur-invariant representation of the image, and utilize such information to make algorithms that are insensitive to blur. The work presented here mainly focuses on developing techniques for the extraction and the application of blur-invariant operators. This thesis contains several contributions. First, we propose a generalized framework based on group theory to constructively generate complete blur-invariants. We construct novel operators that are invariant to a large family of blurs occurring in real scenarios: namely, those blurs that can be modeled by a convolution with a point-spread function having rotational symmetry, or combined rotational and axial symmetry. A second important contribution is represented by the utilization of such operators to develop an algorithm for blur-invariant translational image registration. This algorithm is experimentally demonstrated to be more robust than other state-of-the-art registration techniques. The blur-invariant registration algorithm is then used as pre-processing steps to several restoration methods based on image fusion, like depth-of-field extension, and multi-channel blind deconvolution. All the described techniques are then re-interpreted as a particular instance of Wiener deconvolution filtering. Thus, the third main contribution is the generalization of the blur-invariants and the registration techniques to color images, by using respectively a representation of color images based on quaternions, and the quaternion Wiener filter. This leads to the development of a blur-and-noise-robust registration algorithm for color images. We observe experimentally a significant increase in performance in both color texture recognition, and in blurred color image registrationTiivistelmä Kuvauslaitteet ovat aina fyysisten olosuhteiden rajoittamia, mikä usein ilmenee tallennetun kuvan ilmiasun vääristyminä. Yleisimmät vääristymätyypit voidaan jakaa kahteen kategoriaan: geometrisiin ja radiometrisiin distortioihin. Jälkimmäisestä esimerkkejä ovat kirkkauden, kontrastin ja valon laadun muutokset sekä sensorin kohina ja kuvan sumeus. Koska kuvan sumeus voi johtua monista tekijöistä, yleensä ei ole tarkoitukseen sopivaa eikä laskennallisesti kannattavaa kehittää ad hoc algoritmeja erityyppisten sumeuksien korjaamiseen. Sitä vastoin on mahdollista erottaa kuvasta sumeuden invariantin edustuma ja käyttää tätä tietoa sumeudelle epäherkkien algoritmien tuottamiseen. Tässä väitöskirjassa keskitytään esittämään, millaisia eri tekniikoita voidaan käyttää sumeuden invarianttien operaattoreiden muodostamiseen ja sovellusten kehittämiseen. Tämä opinnäyte sisältää useammanlaista tieteellistä vaikuttavuutta. Ensiksi, väitöskirjassa esitellään ryhmäteoriaan perustuva yleinen viitekehys, jolla voidaan generoida sumeuden invariantteja. Konstruoimme uudentyyppisiä operaattoreita, jotka ovat monenlaiselle kuvaustilanteessa ilmenevälle sumeudelle invariantteja. Kyseessä ovat ne rotationaalisesti (ja/tai aksiaalisesti) symmetrisen sumeuden lajit, jotka voidaan mallintaa pistelähteen hajaantumisen funktion (PSF) konvoluutiolla. Toinen tämän väitöskirjan tärkeä tutkimuksellinen anti on esitettyjen sumeuden invarianttien operaattoreiden hyödyntäminen algoritmin kehittelyssä, joka on käytössä translatorisen kuvan rekisteröinnissä. Tällainen algoritmi on tässä tutkimuksessa osoitettu kokeellisesti johtavia kuvien rekisteröintitekniikoita robustimmaksi. Sumeuden invariantin rekisteröinnin algoritmia on käytetty esiprosessointina tässä tutkimuksessa useissa kuvien restaurointimenetelmissä, jotka perustuvat kuvan fuusioon, kuten syväterävyysaluelaajennus ja monikanavainen dekonvoluutio. Kaikki kuvatut tekniikat ovat lopulta uudelleen tulkittu erityistapauksena Wienerin dekonvoluution suodattimesta. Näin ollen tutkimuksen kolmas saavutus on sumeuden invarianttien ja rekisteröintiteknikoiden yleistäminen värikuviin käyttämällä värikuvien kvaternion edustumaa sekä Wienerin kvaternion suodatinta. Havaitsemme kokeellisesti merkittävän parannuksen sekä väritekstuurin tunnistuksessa että sumean kuvan rekisteröinnissä
44
Sud, Seema. „Reduced Rank Adaptive Filtering Applied to Interference Mitigation in Wideband CDMA Systems“. Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27158.
Der volle Inhalt der QuelleAnnotation:
The research presented in this dissertation is on the development and application of advanced reduced rank adaptive signal processing techniques for high data rate wireless code division multiple access (CDMA) communications systems. This is an important area of research in the field of wireless communications. Current systems are moving towards the use of multiple simultaneous users in a given channel to increase system capacity as well as spatial and/or temporal diversity for improved performance in the presence of multipath and fading channels. Furthermore, to accommodate the demand for higher data rates, fast signal processing algorithms are required, which often translate into blind signal detection and estimation and the desire for optimal, low complexity detection techniques. The research presented here shows how minimum mean square error (MMSE) receivers implemented via the multistage Wiener filter (MWF) can be employed at the receiving end of a CDMA system to perform multiuser detection (MUD) or interference suppression (IS) with no loss in performance and significant signal subspace compression better than any previous reduced rank techniques have shown. This is important for optimizing performance because it implies a reduction in the number of required samples, so it lessens the requirement that the channel be stationary for a time duration long enough to obtain enough samples for an accurate MMSE estimate. The structure of these receivers is derived for synchronous and asynchronous systems for a multipath environment, and then it is shown that implementation of the receiver in a reduced rank subspace results in no loss in performance over full rank methods. It is also shown in some instances that reduced rank exceeds full rank performance. Multiuser detectors are also studied, and the optimal reduced rank detector is shown to be equivalent to a bank of parallel single user detectors performing interference suppression (IS). The performance as a function of rank for parallel and joint multiuser detectors are compared. The research is then extended to include joint space-code (i.e. a joint multiuser detector) and joint space-time processing algorithms which employ receiver diversity for low complexity diversity gain. Non-linear techniques, namely serial interference cancellation (SIC) and parallel interference cancellation (PIC), will also be studied. The conventional matched filter correlator will be replaced by the MWF, thereby incorporating IS at each stage of the interference canceller for improved performance. A closed form expression is derived for the probability of error, and performance gains are evaluated. It will be further shown how the receiver structure can be extended when space-time codes are employed at the transmitter for additional diversity gain with minimal impact on complexity. The MMSE solution is derived and implemented via the MWF with some examples. It is believed that these new techniques will have a significant impact on the design of fourth generation (4G) and beyond cellular CDMA systems.Ph. D.
45
Nguyen, Hien. „Robust Steering Vector Mismatch Techniques for Reduced Rank Adaptive Array Signal Processing“. Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29238.
Der volle Inhalt der QuelleAnnotation:
The research presented in this dissertation is on the development of advanced reduced rank adaptive signal processing for airborne radar space-time adaptive processing (STAP) and steering vector mismatch robustness. This is an important area of research in the field of airborne radar signal processing since practical STAP algorithms should be robust against various kinds of mismatch errors. The clutter return in an airborne radar has widely spread Doppler frequencies; therefore STAP, a two-dimensional adaptive filtering algorithm is required for effective clutter and jamming cancellation. Real-world effects in nonhomogeneous environments increase the number of adaptive degrees of freedom required to adequately suppress interference. The increasing computational complexity and the need to estimate the interference from a limited sample support make full rank STAP impractical. The research presented here shows that the reduced rank multistage Wiener filter (MWF) provides significant subspace compression better than any previous techniques in a nonhomogeneous environment. In addition, the impact of steering vector mismatch will also be examined on the MWF. In an airborne radar environment, it is well known that calibration errors and steering vector mismatch can seriously degrade adaptive array performance and result in signal cancellation. These errors can be caused by many non-ideal factors such as beam steering angle errors, multipath propagation, and phase errors due to array imperfections. Since the MWF centrally features the steering vector on its formulation, it is important to assess the impact of steering vector mismatch. In this dissertation, several novel techniques for increasing robustness are examined and applied to the MWF. These include derivative constraints, quiescent pattern control (QPC) techniques, and covariance matrix tapers
(CMT). This research illustrates that a combination of CMT and QPC, denoted CMTQ, is very effective at mitigating the impact of steering vector mismatch. Use of CMTQ augmentation provides the steering vector mismatch robustness that we desire while improving the reduced-rank and reduced sample characteristics of the MWF. Results using Monte Carlo simulations and experimental Multichannel Airborne Radar Measurements (MCARM) data confirm that the use of CMTQ gives superior performance to steering vector errors at a much reduced rank and sample support as compared to conventional techniques.Ph. D.
46
Namroud, Iman. „An Analysis of Aliasing and Image Restoration Performance for Digital Imaging Systems“. University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1399046084.
Der volle Inhalt der Quelle
47
Ammar, Moussa. „Optimisation d'un schéma de codage d'image à base d'une TCD : application à un codeur JPEG pour l'enregistrement numérique à bas débit“. Paris, ENST, 2002. https://pastel.archives-ouvertes.fr/tel-00005739.
Der volle Inhalt der QuelleAnnotation:
Nous considérons dans cette thèse le problème d'otpimisation d'un schéma de codage/décodage JPEG et le post-traitement de réduction des effets de blocs dans les images codées par JPEG. Nous proposons tout d'abord le filtrage de Wiener comme optimisation du banc de filtres de synthèse pour une distorsion minimale et nous cherchons par la suite une quantifcation optimisée. L'algorithme itératif A1 réalise une optimisation conjointe des quantificateurs et du banc de filtres de synthèse. Les résultats experimentaux sur quelques images montrent que le gain total en terme de PSNR peut atteindre 1,36dB et les améliorations visuelles confirment ces résultats. Enfin, nous proposons une nouvelle technique de réduction des effets de blocs basée sur la minimisation de l'énergie haute fréquence du bruit de quantification. L'évaluation de l'algorithme B1montre une diminution des effets de blocs, et de nombreuses illustrations permettent d'appréhender visuellement les performances de cette méthodeIn this thesis, we consider the optimization problem of a JPEG Coding/Decoding scheme and the reduction of blocking effects in transform image coding. First we propose to optimize for minimum distortion the synthesis subband filters using the Wiener filters, then to calculate the optimal quantizer step sizes based on a rate-constrained image-adaptive quantization. A1 is the iterative algorithm that optimizes jointly the quantizer step sizes and the synthesis subband filters. The blocking effects in transform image coding are assmilated block boundary discontinuities. These discontinuities represent the quantization error within a block that becomes high frequency quantization noises after reconstruction. To reduce the blocking artefacts we propose the algorithm B1 that minimizes the energy of high frequency quantization noises. A visual inspection of some reconstructed images after applying the algorithm B1 has allowed to evaluate the performance of such technique. ?????
48
Sizov, Vasily. „Wienerovská vlnková filtrace signálů EKG“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-374614.
Der volle Inhalt der QuelleAnnotation:
Tato práce se zabývá možností využití vlnkové transformace v aplikacích, které se zabývají potlačením šumu. Především se jedná o oblast filtrace signálu EKG. Úkolem je zhodnotit vliv různých parametrů nastavení samotné filtrace a zjistit jaký vliv má různé nastavení prahování wavelet koeficientů. Výsledkem práce je také stanovení hodnot prahů, stanovení nejlepšího způsobu rozkladu signálu a volba rekonstrukčních bank filtrů. Text obsahuje výsledky Wienerovy filtrace, při které byly testovány různé banky rozkladových a rekonstrukčních filtrů.Všechny popsané filtrační metody byly testovány na reálných záznamech EKG s aditivním myopotenciálním šumem. Algoritmy byly realizovány v prostředí MATLAB.
49
Jeanvoine, Arnaud. „Intérêt des algorithmes de réduction de bruit dans l'implant cochléaire : Application à la binauralité“. Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00875826.
Der volle Inhalt der QuelleAnnotation:
Les implants cochléaires sont des appareils destinés à la réhabilitationdes surdités profondes et totales. Ils assurent la stimulation du nerf auditif en plaçant des électrodes dans la cochlée. Différentes études ont été établis afin d'améliorer l'intelligibilité de la parole dans le bruit chez le patientporteur de cet appareil. Les techniques bilatérales et binaurales permettent dereproduire une audition binaurale, car les deux oreilles sont simulées (commepour les personnes normo-entendantes). Ainsi la localisation et la perceptiondes sons environnants sont améliorées par rapport à une implantationmonaurale. Toutefois, les capacit'es de reconnaissances des mots sont trèsvite limitées en pr'esence de bruits. Nous avons d'evelopp'es des techniquesde r'eduction de bruit afin d'augmenter les performances de reconnaissance.Des améliorations de 10% à 15% suivant les conditions ont été observées. Néanmoins, si la perception est améliorée par les algorithmes, ils focalisent sur une direction, et ainsi, la localisation est alors réduite à l'angle delocalisation. Une seconde étude a alors été effectuée pour mesurer l'effetdes algorithmes sur la localisation. Ainsi, le beamformer donne les meilleurs résultats de compréhension mais la moins bonne localisation. La ré-injectiond'un pourcentage du signal d'entrée sur la sortie a permis de compenser laperte de la localisation sans détériorer l'intelligibilité. Le résultat de ces deux expériences montre qu'il faut un compromis entre laperception et la localisation des sons pour obtenir les meilleures performances.
50
Rao, Peddi Srinivas, und Vallabhaneni Sreelatha. „Implementation and Evaluation of Spectral Subtraction with Minimum Statistics using WOLA and FFT Modulated Filter Banks“. Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2906.
Der volle Inhalt der QuelleAnnotation:
In communication system environment speech signal is corrupted due to presence of additive acoustic noise, so with this distortion the effective communication is degraded in terms of the quality and intelligibility of speech. Now present research is going how effectively acoustic noise can be eliminated without affecting the original speech quality, this tends to be our challenging in this current research thesis work. Here this work proposes multi-tiered detection method that is based on time-frequency analysis (i.e. filter banks concept) of the noisy speech signals, by using standard speech enhancement method based on the proven spectral subtraction, for single channel speech data and for a wide range of noise types at various noise levels. There were various variants have been introduced to standard spectral subtraction proposed by S.F.Boll. In this thesis we designed and implemented a novel approach of Spectral Subtraction based on Minimum Statistics [MinSSS]. This means that the power spectrum of the non-stationary noise signal is estimated by finding the minimum values of a smoothed power spectrum of the noisy speech signal and thus circumvents the speech activity detection problem. This approach is also capable of dealing with non-stationary noise signals. In order to analyze the system in time frequency domain, we have implemented two different filter bank approaches such as Weighted OverLap Added (WOLA) and Fast Fourier Transform Modulated (FFTMod). The proposed systems were implemented and evaluated offline using simulation tool Matlab and then validated their performances based on the objective quality measures such as Signal to Noise Ratio Improvement (SNRI) and Perceptual Evaluation Speech Quality (PESQ) measure. The systems were tested with a pure speech combination of male and female sampled at 8 kHz, these signals were corrupted with various kinds of noises at different noise power levels. The MinSSS algorithm implemented using FFTMod filter bank approach outperforms when compared the WOLA filter bank approach.