The Experts below are selected from a list of 1086 Experts worldwide ranked by ideXlab platform
Peter Vary - One of the best experts on this subject based on the ideXlab platform.
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Least-Squares Design of DFT Filter-Banks Based on Allpass Transformation of Higher Order
IEEE Transactions on Signal Processing, 2010Co-Authors: Heinrich W. Löllmann, Peter VaryAbstract:The allpass transformation of higher order is a very general concept to construct a frequency warped analysis-Synthesis Filter Bank (AS FB) with nonuniform time-frequency resolution. In contrast to the more common allpass transformation of first order, the delay elements of the analysis Filter Bank are substituted by allpass Filters of higher order to achieve a more flexible control over its frequency selectivity. Known analytical closed-form designs for the Synthesis Filter Bank can ensure perfect reconstruction (PR), but the Synthesis subband Filters are not necessarily stable and exhibit no distinctive bandpass characteristic. These problems are addressed by a new least-squares error (LSE) Filter Bank design. The coefficients of the finite-impulse-response (FIR) Synthesis Filters are determined simply by a linear set of equations where the signal delay is an adjustable design parameter. This approach can achieve a perfect signal reconstruction with Synthesis Filters which are inherently stable and feature a bandpass characteristic. The proposed Filter Bank is of interest for various subband processing systems requiring nonuniform frequency bands.
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EUSIPCO - General least-squares design of allpass transformed DFT Filter-Banks
2009Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:The allpass transformation is a common approach to design a frequency warped analysis-Synthesis Filter-Bank (AS FB) with non-uniform time-frequency resolution. Such Filter-Banks are beneficial, e.g., for speech and audio subband processing, but their Synthesis Filter-Bank design is more complex as for uniform Filter-Banks. This problem is tackled by a new least-squares error (LS) Synthesis Filter-Bank design. Magnitude and phase distortions are minimized with the constraints for complete aliasing cancellation and a restricted signal delay. The coefficients of the Synthesis Filters are determined by a linear set of equations with linear constraints which can be easily solved. The obtained FIR Synthesis subband Filters exhibit a frequency selectivity similar to that of the IIR analysis Filters. The new concept is very general and can be applied in case of an allpass transformation of first or higher order as well as for polyphase network (PPN) Filter-Banks where the prototype Filter length exceeds the number of channels. These properties make the proposed design of interest for various subband processing systems requiring non-uniform frequency bands.
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General least-squares design of allpass transformed DFT Filter-Banks
2009 17th European Signal Processing Conference, 2009Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:The allpass transformation is a common approach to design a frequency warped analysis-Synthesis Filter-Bank (AS FB) with non-uniform time-frequency resolution. Such Filter-Banks are beneficial, e.g., for speech and audio subband processing, but their Synthesis Filter-Bank design is more complex as for uniform Filter-Banks. This problem is tackled by a new least-squares error (LS) Synthesis Filter-Bank design. Magnitude and phase distortions are minimized with the constraints for complete aliasing cancellation and a restricted signal delay. The coefficients of the Synthesis Filters are determined by a linear set of equations with linear constraints which can be easily solved. The obtained FIR Synthesis subband Filters exhibit a frequency selectivity similar to that of the IIR analysis Filters. The new concept is very general and can be applied in case of an allpass transformation of first or higher order as well as for polyphase network (PPN) Filter-Banks where the prototype Filter length exceeds the number of channels. These properties make the proposed design of interest for various subband processing systems requiring non-uniform frequency bands.
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ICASSP - Least-squares design of subsampled allpass transformed DFT Filter-Banks with LTI property
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:A new design approach for an allpass transformed analysis-Synthesis Filter-Bank (AS FB) with subsampling is proposed, which can be used for adaptive subband processing with non-uniform time-frequency resolution. Signal reconstruction is performed by an FIR Synthesis Filter-Bank whose coefficients are determined by two different linear least-squares (LS) error designs. The presented unconstrained LS optimization leads to perfect reconstruction (PR), but an insufficient bandpass characteristic for the Synthesis subband Filters. This problem is solved by a second, equality constrained least-squares (CLS) error design, which achieves near-perfect reconstruction (NPR). In the process, the linear distortions are minimized with the constraint for a linear, time-invariant (LTI) overall transfer function. The aliasing-free reconstruction error is significantly lower than for known designs of allpass transformed DFT Filter-Banks with NPR. Moreover, the new Filter-Bank design allows for a low and adjustable signal delay.
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Least-squares design of subsampled allpass transformed DFT Filter-Banks with LTI property
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:A new design approach for an allpass transformed analysis-Synthesis Filter-Bank (AS FB) with subsampling is proposed, which can be used for adaptive subband processing with non-uniform time-frequency resolution. Signal reconstruction is performed by an FIR Synthesis Filter-Bank whose coefficients are determined by two different linear least-squares (LS) error designs. The presented unconstrained LS optimization leads to perfect reconstruction (PR), but an insufficient bandpass characteristic for the Synthesis subband Filters. This problem is solved by a second, equality constrained least-squares (CLS) error design, which achieves near-perfect reconstruction (NPR). In the process, the linear distortions are minimized with the constraint for a linear, time-invariant (LTI) overall transfer function. The aliasing-free reconstruction error is significantly lower than for known designs of allpass transformed DFT Filter-Banks with NPR. Moreover, the new Filter-Bank design allows for a low and adjustable signal delay.
Heinrich W. Löllmann - One of the best experts on this subject based on the ideXlab platform.
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Least-Squares Design of DFT Filter-Banks Based on Allpass Transformation of Higher Order
IEEE Transactions on Signal Processing, 2010Co-Authors: Heinrich W. Löllmann, Peter VaryAbstract:The allpass transformation of higher order is a very general concept to construct a frequency warped analysis-Synthesis Filter Bank (AS FB) with nonuniform time-frequency resolution. In contrast to the more common allpass transformation of first order, the delay elements of the analysis Filter Bank are substituted by allpass Filters of higher order to achieve a more flexible control over its frequency selectivity. Known analytical closed-form designs for the Synthesis Filter Bank can ensure perfect reconstruction (PR), but the Synthesis subband Filters are not necessarily stable and exhibit no distinctive bandpass characteristic. These problems are addressed by a new least-squares error (LSE) Filter Bank design. The coefficients of the finite-impulse-response (FIR) Synthesis Filters are determined simply by a linear set of equations where the signal delay is an adjustable design parameter. This approach can achieve a perfect signal reconstruction with Synthesis Filters which are inherently stable and feature a bandpass characteristic. The proposed Filter Bank is of interest for various subband processing systems requiring nonuniform frequency bands.
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EUSIPCO - General least-squares design of allpass transformed DFT Filter-Banks
2009Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:The allpass transformation is a common approach to design a frequency warped analysis-Synthesis Filter-Bank (AS FB) with non-uniform time-frequency resolution. Such Filter-Banks are beneficial, e.g., for speech and audio subband processing, but their Synthesis Filter-Bank design is more complex as for uniform Filter-Banks. This problem is tackled by a new least-squares error (LS) Synthesis Filter-Bank design. Magnitude and phase distortions are minimized with the constraints for complete aliasing cancellation and a restricted signal delay. The coefficients of the Synthesis Filters are determined by a linear set of equations with linear constraints which can be easily solved. The obtained FIR Synthesis subband Filters exhibit a frequency selectivity similar to that of the IIR analysis Filters. The new concept is very general and can be applied in case of an allpass transformation of first or higher order as well as for polyphase network (PPN) Filter-Banks where the prototype Filter length exceeds the number of channels. These properties make the proposed design of interest for various subband processing systems requiring non-uniform frequency bands.
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General least-squares design of allpass transformed DFT Filter-Banks
2009 17th European Signal Processing Conference, 2009Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:The allpass transformation is a common approach to design a frequency warped analysis-Synthesis Filter-Bank (AS FB) with non-uniform time-frequency resolution. Such Filter-Banks are beneficial, e.g., for speech and audio subband processing, but their Synthesis Filter-Bank design is more complex as for uniform Filter-Banks. This problem is tackled by a new least-squares error (LS) Synthesis Filter-Bank design. Magnitude and phase distortions are minimized with the constraints for complete aliasing cancellation and a restricted signal delay. The coefficients of the Synthesis Filters are determined by a linear set of equations with linear constraints which can be easily solved. The obtained FIR Synthesis subband Filters exhibit a frequency selectivity similar to that of the IIR analysis Filters. The new concept is very general and can be applied in case of an allpass transformation of first or higher order as well as for polyphase network (PPN) Filter-Banks where the prototype Filter length exceeds the number of channels. These properties make the proposed design of interest for various subband processing systems requiring non-uniform frequency bands.
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ICASSP - Least-squares design of subsampled allpass transformed DFT Filter-Banks with LTI property
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:A new design approach for an allpass transformed analysis-Synthesis Filter-Bank (AS FB) with subsampling is proposed, which can be used for adaptive subband processing with non-uniform time-frequency resolution. Signal reconstruction is performed by an FIR Synthesis Filter-Bank whose coefficients are determined by two different linear least-squares (LS) error designs. The presented unconstrained LS optimization leads to perfect reconstruction (PR), but an insufficient bandpass characteristic for the Synthesis subband Filters. This problem is solved by a second, equality constrained least-squares (CLS) error design, which achieves near-perfect reconstruction (NPR). In the process, the linear distortions are minimized with the constraint for a linear, time-invariant (LTI) overall transfer function. The aliasing-free reconstruction error is significantly lower than for known designs of allpass transformed DFT Filter-Banks with NPR. Moreover, the new Filter-Bank design allows for a low and adjustable signal delay.
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Least-squares design of subsampled allpass transformed DFT Filter-Banks with LTI property
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:A new design approach for an allpass transformed analysis-Synthesis Filter-Bank (AS FB) with subsampling is proposed, which can be used for adaptive subband processing with non-uniform time-frequency resolution. Signal reconstruction is performed by an FIR Synthesis Filter-Bank whose coefficients are determined by two different linear least-squares (LS) error designs. The presented unconstrained LS optimization leads to perfect reconstruction (PR), but an insufficient bandpass characteristic for the Synthesis subband Filters. This problem is solved by a second, equality constrained least-squares (CLS) error design, which achieves near-perfect reconstruction (NPR). In the process, the linear distortions are minimized with the constraint for a linear, time-invariant (LTI) overall transfer function. The aliasing-free reconstruction error is significantly lower than for known designs of allpass transformed DFT Filter-Banks with NPR. Moreover, the new Filter-Bank design allows for a low and adjustable signal delay.
J.-c. Pesquet - One of the best experts on this subject based on the ideXlab platform.
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Oversampled Inverse Complex Lapped Transform Optimization
2007 IEEE International Conference on Acoustics Speech and Signal Processing - ICASSP '07, 2007Co-Authors: J. Gauthier, L. Duval, J.-c. PesquetAbstract:When an oversampled FIR Filter Bank structure is used for signal analysis, a main problem is to guarantee its invertibility and to be able to determine an inverse Synthesis Filter Bank. As the analysis scheme corresponds to a redundant decomposition, there is no unique inverse Filter Bank and some of the solutions can lead to artifacts in textured image Filtering applications. In this paper, the flexibility in the choice of the inverse Filter Bank is exploited to find the best-localized impulse responses. The design is performed by solving a constrained optimization problem which is reformulated in a smaller dimensional space. Application to seismic data clearly shows the improvements brought by the optimization process.
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Low Redundancy Oversampled Lapped Transforms and Application to 3D Seismic Data Filtering
2006 IEEE International Conference on Acoustics Speech and Signal Processing Proceedings, 2006Co-Authors: J. Gauthier, L. Duval, J.-c. PesquetAbstract:In a previous work, we proposed a relatively simple method to build non separable perfect reconstruction oversampled lapped transforms. The main drawback of this method was that the redundancy factor was constrained to be equal to the overlapping one. This constitutes a strong limitation for applications such as seismic processing involving three-dimensional data sets. The memory requirements may indeed become hard to meet if the redundancy is not reduced. In this paper, we propose an approach to guarantee that a given lapped transform is invertible by a finite length Filter Bank. We show how to compute a corresponding Synthesis Filter Bank. The proposed analysis/Synthesis Filter Bank system is applied to directional Filtering of noisy three-dimensional seismic data
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ICASSP (2) - Low Redundancy Oversampled Lapped Transforms and Application to 3D Seismic Data Filtering
2006 IEEE International Conference on Acoustics Speed and Signal Processing Proceedings, 2006Co-Authors: J. Gauthier, L. Duval, J.-c. PesquetAbstract:In a previous work, we proposed a relatively simple method to build non separable perfect reconstruction oversampled lapped transforms. The main drawback of this method was that the redundancy factor was constrained to be equal to the overlapping one. This constitutes a strong limitation for applications such as seismic processing involving three-dimensional data sets. The memory requirements may indeed become hard to meet if the redundancy is not reduced. In this paper, we propose an approach to guarantee that a given lapped transform is invertible by a finite length Filter Bank. We show how to compute a corresponding Synthesis Filter Bank. The proposed analysis/Synthesis Filter Bank system is applied to directional Filtering of noisy three-dimensional seismic data.
J. Gauthier - One of the best experts on this subject based on the ideXlab platform.
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Oversampled Inverse Complex Lapped Transform Optimization
2007 IEEE International Conference on Acoustics Speech and Signal Processing - ICASSP '07, 2007Co-Authors: J. Gauthier, L. Duval, J.-c. PesquetAbstract:When an oversampled FIR Filter Bank structure is used for signal analysis, a main problem is to guarantee its invertibility and to be able to determine an inverse Synthesis Filter Bank. As the analysis scheme corresponds to a redundant decomposition, there is no unique inverse Filter Bank and some of the solutions can lead to artifacts in textured image Filtering applications. In this paper, the flexibility in the choice of the inverse Filter Bank is exploited to find the best-localized impulse responses. The design is performed by solving a constrained optimization problem which is reformulated in a smaller dimensional space. Application to seismic data clearly shows the improvements brought by the optimization process.
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Low Redundancy Oversampled Lapped Transforms and Application to 3D Seismic Data Filtering
2006 IEEE International Conference on Acoustics Speech and Signal Processing Proceedings, 2006Co-Authors: J. Gauthier, L. Duval, J.-c. PesquetAbstract:In a previous work, we proposed a relatively simple method to build non separable perfect reconstruction oversampled lapped transforms. The main drawback of this method was that the redundancy factor was constrained to be equal to the overlapping one. This constitutes a strong limitation for applications such as seismic processing involving three-dimensional data sets. The memory requirements may indeed become hard to meet if the redundancy is not reduced. In this paper, we propose an approach to guarantee that a given lapped transform is invertible by a finite length Filter Bank. We show how to compute a corresponding Synthesis Filter Bank. The proposed analysis/Synthesis Filter Bank system is applied to directional Filtering of noisy three-dimensional seismic data
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ICASSP (2) - Low Redundancy Oversampled Lapped Transforms and Application to 3D Seismic Data Filtering
2006 IEEE International Conference on Acoustics Speed and Signal Processing Proceedings, 2006Co-Authors: J. Gauthier, L. Duval, J.-c. PesquetAbstract:In a previous work, we proposed a relatively simple method to build non separable perfect reconstruction oversampled lapped transforms. The main drawback of this method was that the redundancy factor was constrained to be equal to the overlapping one. This constitutes a strong limitation for applications such as seismic processing involving three-dimensional data sets. The memory requirements may indeed become hard to meet if the redundancy is not reduced. In this paper, we propose an approach to guarantee that a given lapped transform is invertible by a finite length Filter Bank. We show how to compute a corresponding Synthesis Filter Bank. The proposed analysis/Synthesis Filter Bank system is applied to directional Filtering of noisy three-dimensional seismic data.
Guido Dartmann - One of the best experts on this subject based on the ideXlab platform.
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EUSIPCO - General least-squares design of allpass transformed DFT Filter-Banks
2009Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:The allpass transformation is a common approach to design a frequency warped analysis-Synthesis Filter-Bank (AS FB) with non-uniform time-frequency resolution. Such Filter-Banks are beneficial, e.g., for speech and audio subband processing, but their Synthesis Filter-Bank design is more complex as for uniform Filter-Banks. This problem is tackled by a new least-squares error (LS) Synthesis Filter-Bank design. Magnitude and phase distortions are minimized with the constraints for complete aliasing cancellation and a restricted signal delay. The coefficients of the Synthesis Filters are determined by a linear set of equations with linear constraints which can be easily solved. The obtained FIR Synthesis subband Filters exhibit a frequency selectivity similar to that of the IIR analysis Filters. The new concept is very general and can be applied in case of an allpass transformation of first or higher order as well as for polyphase network (PPN) Filter-Banks where the prototype Filter length exceeds the number of channels. These properties make the proposed design of interest for various subband processing systems requiring non-uniform frequency bands.
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General least-squares design of allpass transformed DFT Filter-Banks
2009 17th European Signal Processing Conference, 2009Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:The allpass transformation is a common approach to design a frequency warped analysis-Synthesis Filter-Bank (AS FB) with non-uniform time-frequency resolution. Such Filter-Banks are beneficial, e.g., for speech and audio subband processing, but their Synthesis Filter-Bank design is more complex as for uniform Filter-Banks. This problem is tackled by a new least-squares error (LS) Synthesis Filter-Bank design. Magnitude and phase distortions are minimized with the constraints for complete aliasing cancellation and a restricted signal delay. The coefficients of the Synthesis Filters are determined by a linear set of equations with linear constraints which can be easily solved. The obtained FIR Synthesis subband Filters exhibit a frequency selectivity similar to that of the IIR analysis Filters. The new concept is very general and can be applied in case of an allpass transformation of first or higher order as well as for polyphase network (PPN) Filter-Banks where the prototype Filter length exceeds the number of channels. These properties make the proposed design of interest for various subband processing systems requiring non-uniform frequency bands.
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ICASSP - Least-squares design of subsampled allpass transformed DFT Filter-Banks with LTI property
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:A new design approach for an allpass transformed analysis-Synthesis Filter-Bank (AS FB) with subsampling is proposed, which can be used for adaptive subband processing with non-uniform time-frequency resolution. Signal reconstruction is performed by an FIR Synthesis Filter-Bank whose coefficients are determined by two different linear least-squares (LS) error designs. The presented unconstrained LS optimization leads to perfect reconstruction (PR), but an insufficient bandpass characteristic for the Synthesis subband Filters. This problem is solved by a second, equality constrained least-squares (CLS) error design, which achieves near-perfect reconstruction (NPR). In the process, the linear distortions are minimized with the constraint for a linear, time-invariant (LTI) overall transfer function. The aliasing-free reconstruction error is significantly lower than for known designs of allpass transformed DFT Filter-Banks with NPR. Moreover, the new Filter-Bank design allows for a low and adjustable signal delay.
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Least-squares design of subsampled allpass transformed DFT Filter-Banks with LTI property
2008 IEEE International Conference on Acoustics Speech and Signal Processing, 2008Co-Authors: Heinrich W. Löllmann, Guido Dartmann, Peter VaryAbstract:A new design approach for an allpass transformed analysis-Synthesis Filter-Bank (AS FB) with subsampling is proposed, which can be used for adaptive subband processing with non-uniform time-frequency resolution. Signal reconstruction is performed by an FIR Synthesis Filter-Bank whose coefficients are determined by two different linear least-squares (LS) error designs. The presented unconstrained LS optimization leads to perfect reconstruction (PR), but an insufficient bandpass characteristic for the Synthesis subband Filters. This problem is solved by a second, equality constrained least-squares (CLS) error design, which achieves near-perfect reconstruction (NPR). In the process, the linear distortions are minimized with the constraint for a linear, time-invariant (LTI) overall transfer function. The aliasing-free reconstruction error is significantly lower than for known designs of allpass transformed DFT Filter-Banks with NPR. Moreover, the new Filter-Bank design allows for a low and adjustable signal delay.
