Showing papers on "Quadrature mirror filter published in 1990"

Multirate digital filters, filter banks, polyphase networks, and applications: a tutorial

Abstract: The basic concepts and building blocks in multirate digital signal processing (DSP), including the digital polyphase representation, are reviewed. Recent progress, as reported by several authors in this area, is discussed. Several applications are described, including subband coding of waveforms, voice privacy systems, integral and fractional sampling rate conversion (such as in digital audio), digital crossover networks, and multirate coding of narrowband filter coefficients. The M-band quadrature mirror filter (QMF) bank is discussed in considerable detail, including an analysis of various errors and imperfections. Recent techniques for perfect signal reconstruction in such systems are reviewed. The connection between QMF banks and other related topics, such as block digital filtering and periodically time-varying systems, is examined in a pseudo-circulant-matrix framework. Unconventional applications of the polyphase concept are discussed. >

Analysis/synthesis techniques for subband image coding

Abstract: Analysis/synthesis systems designed for low bit rate image coding, their impact on overall system quality, and their computational complexity are discussed The investigation focuses on the design of analysis/synthesis systems for image coding and the perceptual impact of these systems at low bit rates Two objectives are emphasized in developing these systems: confining the total size of the subband images to be equal to the original image size, and designing the filters so that perceptual distortion is not introduced by the analysis/synthesis system Methods based on circular convolution and symmetric extensions are developed and discussed in detail The theory, design, and implementation of both recursive and nonrecursive filtering systems are discussed Methods are introduced which display advantages over conventional quadrature mirror filter based approaches >

Non-separable extensions of quadrature mirror filters to multiple dimensions

Abstract: Generalized non-separable extensions of quadrature mirror filter (QMF) banks to two and three dimensions, in which the orientation specificity of the high-pass filters is greatly improved, are described. In particular, extensions to two dimensions with hexagonal symmetry, and 3-D spatiotemporal extensions with rhombic-dodecahedral symmetry, are discussed. Although these filters are conceived and designed on nonstandard sampling lattices, they can be applied to rectangularly sampled images. As in one dimension, these transformations can be hierarchically cascaded to form a multiscale pyramid representation. A set of example filters is designed and applied to the problems of image compression, progressive transmission, orientation analysis, and motion analysis. >

Modulated QMF filter banks with perfect reconstruction

Abstract: Necessary and sufficient conditions for perfect reconstruction (PR) in a modulated filter bank are derived. It is shown that, for a bank of M filters of length L, PR can be obtained when L = 2KM, for any positive integer K, whereas previous results guaranteed PR only for K = 1.

Structures for M-channel perfect-reconstruction FIR QMF banks which yield linear-phase analysis filters

Abstract: The authors develop structures for FIR (finite impulse response) perfect-reconstruction QMF (quadrature mirror filter) banks, which cover a subclass of systems that yield linear-phase analysis filters for arbitrary M. The parameters of these structures can be optimized to design analysis filters with minimum stopband energy which at the same time have linear phase and satisfy the perfect-reconstruction property. If there are M subbands, then depending on whether the coefficients h/sub k/(n) of each analysis filter are symmetric or antisymmetric, several combinations of filter banks are possible. Some of these permit perfect reconstruction and some do not. For a given M, the authors develop a formula for the number of combinations for a subclass of linear-phase perfect-reconstruction structures. As an example, they elaborate on a perfect-reconstruction linear-phase lattice structure for three channels. The lattice structure is such that, regardless of the parameter values, the QMF bank enjoys the perfect-reconstruction property while at the same time the analysis filters have linear phase. A design example is presented, along with tables of impulse response coefficients. >

High speed A/D conversion using QMF banks

Abstract: A structure for analog-to-digital (A/D) conversion capable of attaining high resolution and high speed using lower-resolution, lower-speed A/D converters is presented. The structure is based on quadrature mirror filter (QMF) banks, except that the analysis filter bank is a switched-capacitor circuit whereas the synthesis bank is a digital filter circuit. The structure incorporates the advantages of subband coding, and considerably reduces the effect of mismatches among the low-resolution A/D converters. An illustrative example and experimental results verifying the good performance of the proposed approach are included. >

Motion adaptive luminance signal and color signal separating filter

Abstract: A filter for separating a color signal and a luminance signal from a composite color television signal in which the frequency of said color signal is multiplexed in a high-frequency region of the luminance signal. In response to the movement of a picture, an appropriate filter is selected from a filter utilizing interframe correlation, a filter utilizing interfield correlation and a filter utiliz-ing the infield correlation. A plurality of filters utilizing filed correlation are prepared and a color signal and a luminance signal are separated by the processing of a principal pixel, which is an object of processing, and pixels different from each other. A filter is selected in accordance with the correlation state between the principal pixel and the pixels therearound.

How to capture all FIR perfect reconstruction QMF banks with unimodular matrices

Abstract: The problem of perfect reconstruction in maximally decimated FIR (finite impulse response) QMF (quadrature mirror filter) banks is revisited. A necessary and sufficient condition for perfect reconstruction in this system is that the polyphase matrix of the analysis bank must have a determinant equal to a delay. The author explores various avenues to completely parameterize such matrices. It is shown that the problem can always be decomposed into two problems: one of parameterizing lossless matrices, and one of parameterizing unimodular matrices. Several possibilities for unimodular parameterization are explored. >

Application of the Princen-Bradley filter bank to speech and image compression

Abstract: The authors provide an efficient fast Fourier transform implementation, a set of optimal windows, and a new proof of the perfect reconstruction property for a critically sampled filter bank introduced by Princen and Bradley. Based on the new proof, necessary conditions for perfect reconstruction are also derived for the oversampled case. This filter bank is well suited to compression of speech and images due to its good frequency resolution, overlapped output, computational efficiency, and low delay. The authors evaluated its performance in a 32 band, 16-kb/s adaptive speech compression system, and found both its objective and subjective performance to be comparable to a more complex quadrature mirror filter bank. In image coding experiments, the Princen-Bradley filter bank demonstrated quality similar to DCT-based systems at high rates and reduced blocking artifacts at rates of 0.25-0.5 bpp. A psychophysically based bit allocation algorithm that provides a significant perceptual improvement over a related algorithm that seeks to minimize the mean-square error is introduced. >

On factorization of a subclass of 2-D digital FIR lossless matrices for 2-D QMF bank applications

Abstract: The role of one-dimensional (1-D) digital finite impulse response (FIR) lossless matrices in the design of FIR perfect reconstruction quadrature mirror filter (QMF) banks has been explored previously. Structures which can realize the complete family of FIR lossless transfer matrices, have also been developed, with QMF application in mind. For the case of 2-D QMF banks, the same concept of lossless polyphase matrix has been used to obtain perfect reconstruction. However, the problem of finding a structure to cover all 2-D FIR lossless matrices of a given degree has not been solved. Progress in this direction is reported. A structure which completely covers a well-defined subclass of 2-D digital FIR lossless matrices is obtained. >

Method and apparatus for canceling quadrature distortion as for video signals having in-phase and quadrature phase components

Abstract: High definition or enhanced television signals include supplementary information which is double-sideband modulated in quadrature with the picture carrier, and passed through an inverse Nyquist filter before being combined with a conventional vestigial sideband modulated main video signal. A receiver which recovers both the main video signal and the supplementary information processes the received video signal through an IF filter having a vestigial sideband frequency response characteristic. Two synchronous detectors recover in-phase and quadrature phase signal components from the filtered television signals, these recovered signals each include quadrature crosstalk distortion components from the other signal. The crosstalk from the supplementary signal into the main signal is canceled by filtering the recovered quadrature signal and adding the result to the recovered in-phase signal. This filtering also equalizes the in-phase signal by converting the quadrature distortion components in the recovered quadrature signal into reenforcing signal components in the in-phase signal. This signal recovery system is advantageously used with a ghost cancellation system.

Coding of advanced TV for BISDN using multiple subbands

Abstract: A subband-based coding scheme for the digital transmission of advanced television (ATV) signals within broadband ISDN (BISDN) is described. It is intended for the delivery of high-quality video to the home or office at the CCITT recommended H4 rate of roughly 130 Mb/s. The scheme uses intrafield processing only, resulting in relatively low complexity for hardware implementation, very desirable error propagation properties and the elimination of motion-related artifacts. The use of the shortest kernal (two-tap) quadrature mirror filter (QMF) pairs for signal decomposition and reconstruction minimizes quantization noise spread and further reduces complexity. Through successive QMF operations, the signal is decomposed into six bands to achieve low noise coding not normally associated with the shortest kernal implementations. In effect, the coding scheme is identical to a Hadamard transform (HT) with nonconstant block sizes. When combined with entropy coding, this approach achieves the roughly 5.6:1 compression desired while retaining very high image quality. >

Quadrature amplitude modulation wave demodulator provided with band-pass filters for fixed equalizer

Abstract: A quadrature amplitude modulation wave demodulator which includes a fixed equalizer having a first band-pass filter applied with a quadrature amplitude modulation wave reception signal for outputting an in-phase component with respect to a carrier wave for the reception signal, and a second band-pass filter applied with the reception signal for outputting a quadrature component with respect to the carrier wave for the reception signal. There is provided a vector multiplication section for performing vector multiplication between one vector having outputs of the first and second band-pass filters as two components, and another vector having two reference carrier waves in quadrature to each other as two components.

Discrete-time wavelet transforms and their generalizations

Abstract: Based on the continuous-time wavelet transforms, transforms for the expansion of discrete-time signals are derived. Biorthogonal discrete wavelet expansions are exactly implemented in critically sampled quadrature mirror filter banks. Scale-variant pseudowavelet transforms are defined as a natural generalization. Lattice parametrization of both finite- and infinite-response quadrature mirror filters leads to efficient implementations of orthogonal discrete wavelet transforms and allows for optimization techniques for the choice of basis. >

Efficient 2-D analysis/synthesis filter banks for directional image component representation

Abstract: A filter bank for the directional decomposition of images is described. The filter bank represents a union of two powerful image processing tools: directional decomposition and subband decomposition. The directional components correspond to wedge-shaped regions in the frequency spectrum. The filter bank is implemented in a tree structure where each two-band system is maximally decimated and provides either exact or aliasing free reconstruction. The design of the analysis/synthesis filter is such that the filter bank can be implemented in an extremely efficient computational form. The design method described uses conventional 1-D analysis/synthesis filters as prototypes and thereby circumvents designing 2-D filters. >

Subband coding of video with adaptive vector quantization

Abstract: A low bit rate adaptive video coding technique is proposed. The redundancy within adjacent video frames is exploited by motion-compensated interframe prediction, and the motion-compensated frame difference (MCFD) signal is decomposed by using a quadrature mirror filter (QMF) structure. The subband signals are vector quantized adaptively. The MCFD signals are low correlated, hence transform coding techniques are not very suitable for this kind of signal source. At 0.25-0.3 bits/pixel range, 38-40-dB peak-to-peak signal-to-noise ratio is achieved with the proposed scheme for four monochrome test sequences used: cindy, mono, duo, and quartet. The visual quality of the encoded test sequences is good, almost indistinguishable from the originals. The proposed technique outperforms the adaptive transform coding and adaptive vector quantization techniques for the tested sequences. >

A new approach to the design of FIR perfect reconstruction QMF banks

Abstract: A design method for perfect reconstruction quadrature mirror filter (PR-QMF) banks based on obtaining good initializing points is presented. For the two-channel PR-QMF design, the initializing point is obtained from a traditional QMF design, while in the M-channel case (M>2), it is obtained from a pseudo-QMF design. In both cases, the parameters of the corresponding PR-QMF bank (lattice implementation) are initialized. This leads to considerably faster convergence of the optimization. Design examples are included. >

Sub-band adaptive IIR noise cancellation

Abstract: A subband adaptive infinite impulse response (IIR) noise cancellation scheme whose structure enables the cancellation of multiple sinusoidal interferences in a received speech signal is presented. Compared with the classical least mean square adaptive noise cancellation method, this new structure has two major differences. First, the quadrature mirror filter technique is used to decompose signals into subbands. Second, a new constrained adaptive IIR notch filter and adaptive IIR bandpass filter are developed to form an adaptive IIR noise canceller and used to remove the multiple-frequency, or harmonic, noise from a received speech signal. Computer simulations were done using a set of actual speech signals corrupted by car engine noise. Experiments demonstrate that more than 20-dB signal-to-noise ratio improvements can be achieved. >

One and two-dimensional digital mutirate systems with applications in sub-sampling and bandlimited signal reconstruction

Abstract: This thesis deals with the two-dimensional (2D) multirate quadrature mirror filter (QMF) bank and new applications of 1D and 2D multirate filter bank concepts to the periodic nonuniform sampling and reconstruction of bandlimited signals. The potential use of multirate filter banks in the statistically optimal estimation of signals in the presence of wide-sense cyclostationary noise is also examined. The two-dimensional QMF bank is free from aliasing if and only if a certain polyphase matrix product related to the filter bank possesses the 2D pseudo-circulant property. A 2D FIR filter bank can be designed with the perfect reconstruction property if the polyphase matrix of its analysis filter bank is constrained to be a 2D lossless matrix. A design example is included. The losslessness constraint is satisfied by imposing a cascaded structure of first-degree lossless sections on the polyphase matrix. A limited factroization theorem is derived for 2D FIR lossless systems where the order in one of the two dimensions is limited to unity. In the area of nonuniform sampling of multiband bandlimited signals, the filter bank approach is utilized to derive a computationally efficient method for reconstructing bandlimited signals. The above scheme can also be viewed as a mean of compressing and reconstructing an oversampled bandlimited signal. It is shown that such a scheme has lower computational complexity than traditional methods of sampling rate alteration. The results can be extended to nonuniform sampling in two-dimensions using integer lattices. A further application of the multirate filter bank is in signal estimation in the presence of cyclostationary noise. The necessary and sufficient condition for the filter bank to preserve the wide-sense stationarity of the input is derived. Several applications where cyclostationary noise is present are indicated, and through the use of simulations the performance of the optimal filter bank can be compared with the conventional scalar optimal filter. The roundoff noise in orthogonal matrix building blocks is analyzed, since these building blocks are commonly present in filter bank implementations.

A new 2D quadrature polar separable filter and its applicable to texture analysis

Abstract: The frequency response of the filter consists of two independent parts. The first is a prolate spheroidal sequence that is dependent on the polar radius. The second is a cosine function of the polar angle. The product of these two parts constitutes a 2-D filtering function. The frequency characteristics of the new filter are similar to that of the 2-D Cartesian separable filter which is defined in terms of two prolate spheroidal sequences. However, in contrast to the 2-D Cartesian separable filter, the position and direction of the new filter in the frequency domain is easy to control. Some applications of the new filter in texture processing, such as generation of synthetic texture, estimation of texture orientation, feature extraction, and texture segmentation, are discussed. >

Two-band IIR quadrature mirror filter design

Abstract: Two types of two-band IIR quadrature mirror filter structure are propsed. The aliasing distortion and amplitude distortion can be exactly cancelled. The Remez exchange algorithm is used iteratively to optimise the filter response, which results in an equal-ripple design.

Subband Coding of Images Using the Singular Value Decomposition

Abstract: The singular value decomposition method is proposed for the coding of the subband images generated via a two-dimensional (2-D) quadrature mirror filter analysis bank. This approach permits easy determination of the optimal bit allocation and by decomposing an image into singular vectors, a 2-D coding problem is transformed into a 1-D coding problem, for which a stable linear prediction algorithm exists. In addition, the determination of the SVD of subimages is much simpler than that of the original one, due to their considerably smaller sizes. Simulation results are presented to illustrate the performance characteristics of the proposed approach.

MUL.TIl3AND CELP CODING OF SPEECH

Abstract: In this study, we have considered a novel extension to the CELP model, called the multiband CELP (MCELP) coding. This is an attempt to combine the advantages of waveform-preserving techniques, specifically, the subband coding (SBC) and the vector quantization (VQ), with vocoding techniques. In our implmentation, a quadrature mirror filter (QMF) bank transforms a consecutive sequence of N samples of speech into a matrix of K rows and L columns, where K is the number of subbands and L is the depth of each codeword in a given subband. Splitting a block of N samples into K-bands can be performed either in a complete tree structure or in a pruned tree structure. In the former case, multichannel linear prediction techniques are used to obtain the short-term and longterm prediction vectors. Then "good" codebooks are designed using the matrix quantization (MQ) extension of VQ design techniques. In the latter case, however, the bit assignment can be done using scalar or vector quantization strategies. In all of these cases, the index of the minimum distortion codeword and the side information bits, consisting of the gain, the pitch and the vocal tract model vectors are transmitted to the receiver. The decoder is simply an inverse operation as in all CELP coders. Both SNR and segmental SNR dues are compiled for a number systems; the results were presented to a number of scientists and engineers working in the field in an informal manner and the quality of the reconstructed speech has been graded as roughly comparable to other CELP implementations.

Quadrature and inphase FIR filter design for arbitrary delay compensation

Abstract: A method is presented for generating a pair of filters to separate the inphase and quadrature components of a signal and to compensate for an arbitrary delay. Given a delay, the coefficients of the corresponding pairs of filters are appropriately selected from the coefficients of a common FIR filter. This filter is designed to include the coefficients of filter pairs for a set of delays. For other delays, interpolation is used to obtain the coefficients. It is shown that it is possible to limit interpolation effects to negligible range. Unlike previous approaches, this method has the advantage of requiring the design of only a single filter (the common filter) for all delays. >

ACT quadrature mirror filter banks

Abstract: The authors demonstrate a single ACT (acoustic charge transport) device which comprises a three-filter QMF (quadrature mirror filter) with center frequencies of 0 MHz (baseband), 14.2 MHz, and 23.6 MHz, and bandwidths of 9.45 MHz each. This filter bank produces a digital processing power of 9 billion digital operations per second. Theoretical and experimental data are presented. In addition, a simple technique that simultaneously reduces the baseband response and the output capacitance of the device and is suitable for both voltage sense and current sense designs is presented. The low capacitance voltage sense version has a 10 dB reduction in the baseband response and a 15 dB improvement in output capacitance. >

Facsimile signal processing for Chinese characters

Abstract: A facsimile (fax) signal processing system designed for filtering documents with printed Chinese characters is described. Filtering algorithms are applied to remove noise corrupting the image scanned by the fax machine and to preserve the edges. A total of six filtering algorithms have been chosen for investigation, namely, weighted average filter, separable median filter, median with checking filter, Lee's filter, gradient inverse filter and rotating variance filter. Documents containing Chinese characters are scanned and then stored in the RAM of a personal computer. Random noise is then added, and filtering performed. Experimental results show that all of the six algorithms are capable of removing some of the noise. However, the median filter demonstrated the best noise-removing and edge-preserving capabilities, speed of operation, and ease of implementation for both small- and large-size Chinese characters. >