The Experts below are selected from a list of 17391 Experts worldwide ranked by ideXlab platform
Tor A. Ramstad - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis Filter bank with low memory requirements for image subband coding
1998 IEEE International Symposium on Circuits and Systems (ISCAS), 1998Co-Authors: Ingil Sundsbø, Tor A. RamstadAbstract:One of the factors that makes subband coding seem less attractive for image processing compared to transform coding, is the extensive memory requirements for 2-D Filtering. In this paper we present a Filtering method that significantly lowers the memory requirements. A parallel, uniform and separable Filter bank with 8 channels in each dimension is considered. It is shown that by a data reordering and a minor structural change to the Filter bank, a blockwise Filtering is made possible, thus reducing the total memory to 192 B registers and 9 KB RAM for an image of size 1152/spl times/1920 pixels.
-
Low complexity Synthesis Filter bank for subband coding of images
1996 8th European Signal Processing Conference (EUSIPCO 1996), 1996Co-Authors: Ingil Sundsbø, Tor A. RamstadAbstract:Optimizations are performed to obtain a Filter bank for subband coding of images espescially suited for VLSI implementation. Based on a Filter bank consisting of two FIR Filters combined with an 8 point DCT, we investigate how the quantization of Filter coefficients and twiddle factors in different algorithms affects the quality of the Filter bank. It is found that a DCT based on the Stasinksi algorithm with twiddle factors of only 5 bits together with FIR Filter coefficients of 10 bits, gives a Filter bank with high coding gain, no blocking artifacts and limited ringing. The VLSI complexity is comparable to that of DCT transforms.
-
IIR Filterbank for subband coding of images
1988. IEEE International Symposium on Circuits and Systems, 2024Co-Authors: Tor A. RamstadAbstract:The author presents a simple derivation of a separable two-dimensional uniform Filterbank for subband coding of images. Each one-dimensional Filterbank is tree-structured where the individual quadrature mirror Filters are of the infinite-impulse response (IIR) type. Through the use of a combination of causal and anticausal Filtering in the analysis and Synthesis Filter banks, respectively, perfect signal reconstruction is obtained. A subband coder model including quantization is given, and results concerning optimal Filtering in a subjective sense are presented. >
K R Smith - One of the best experts on this subject based on the ideXlab platform.
-
mwa tied array processing iii microsecond time resolution via a polyphase Synthesis Filter
Publications of the Astronomical Society of Australia, 2020Co-Authors: S J Mcsweeney, S M Ord, D Kaur, N D R Bhat, B W Meyers, S E Tremblay, J Jones, B Crosse, K R SmithAbstract:A new high time resolution observing mode for the Murchison Widefield Array (MWA) is described, enabling full polarimetric observations with up to $30.72\,$ MHz of bandwidth and a time resolution of ${\sim}$ $0.8\,\upmu$ s. This mode makes use of a polyphase Synthesis Filter to ‘undo’ the polyphase analysis Filter stage of the standard MWA’s Voltage Capture System observing mode. Sources of potential error in the reconstruction of the high time resolution data are identified and quantified, with the $S/N$ loss induced by the back-to-back system not exceeding $-0.65\,$ dB for typical noise-dominated samples. The system is further verified by observing three pulsars with known structure on microsecond timescales.
Yuichi Tanaka - One of the best experts on this subject based on the ideXlab platform.
-
two channel critically sampled graph Filter banks with spectral domain sampling
IEEE Transactions on Signal Processing, 2019Co-Authors: Akie Sakiyama, Yuichi Tanaka, Kana Watanabe, Antonio OrtegaAbstract:We propose two-channel critically-sampled Filter banks for signals on undirected graphs that utilize spectral domain sampling. Unlike conventional approaches based on vertex domain sampling, our transforms have the following desirable properties: first, perfect reconstruction regardless of the characteristics of the underlying graphs and graph variation operators; and second, a symmetric structure; i.e., both analysis and Synthesis Filter banks are built using similar building blocks. Along with the structure of the Filter banks, this paper also proves the general criterion for perfect reconstruction and theoretically shows that the vertex and spectral domain sampling coincide for a special case. The effectiveness of our approach is evaluated by comparing its performance in nonlinear approximation and denoising with various conventional graph transforms.
-
UNEQUAL LENGTH FIRST-ORDER LINEAR-PHASE Filter BANKS FOR EFFICIENT IMAGE CODING
2015Co-Authors: Yuichi Tanaka, Masaaki Ikehara, Truong Q. NguyenAbstract:In this paper, we present the structure and design method for a first-order linear-phase Filter bank (FOLPFB) which has unequal Filter lengths in its Synthesis bank (UFLPFB). A FOLPFB is a general-ized version of biorthogonal LPFBs regarding their Synthesis Filter lengths. Ringing artifact is the main disadvantage of image coding based on FOLPFBs. UFLPFBs can reduce the ringing artifacts as well as approximate smooth regions well. Index Terms — First-order linear-phase Filter banks, biorthogo-nal Filter banks, unequal length Filter banks, image coding. 1
-
a simplified lattice structure of first order linear phase Filter banks
European Signal Processing Conference, 2007Co-Authors: Yuichi Tanaka, Masaaki Ikehara, T Q NguyenAbstract:A simplified lattice structure for first-order linear-phase Filter banks (FOLPFBs) is presented in this paper. A FOLPFB is a generalized version of biorthogonal linear-phase Filter banks regarding their Synthesis Filter lengths. FOLPFBs' structure is more complicated and has more parameters than that in other FBs. We propose a method to reduce their redundant parameters without losing their properties. Moreover, regularity can be imposed which reduces the design freedom as well as improves the perceptual quality in image coding.
-
unequal length first order linear phase Filter banks for efficient image coding
International Conference on Image Processing, 2007Co-Authors: Yuichi Tanaka, Masaaki IkeharaAbstract:In this paper, we present the structure and design method for a first-order linear-phase Filter bank (FOLPFB) which has unequal Filter lengths in its Synthesis bank (UFLPFB). A FOLPFB is a generalized version of biorthogonal LPFBs regarding their Synthesis Filter lengths. Ringing artifact is the main disadvantage of image coding based on FOLPFBs. UFLPFBs can reduce the ringing artifacts as well as approximate smooth regions well.
S J Mcsweeney - One of the best experts on this subject based on the ideXlab platform.
-
mwa tied array processing iii microsecond time resolution via a polyphase Synthesis Filter
Publications of the Astronomical Society of Australia, 2020Co-Authors: S J Mcsweeney, S M Ord, D Kaur, N D R Bhat, B W Meyers, S E Tremblay, J Jones, B Crosse, K R SmithAbstract:A new high time resolution observing mode for the Murchison Widefield Array (MWA) is described, enabling full polarimetric observations with up to $30.72\,$ MHz of bandwidth and a time resolution of ${\sim}$ $0.8\,\upmu$ s. This mode makes use of a polyphase Synthesis Filter to ‘undo’ the polyphase analysis Filter stage of the standard MWA’s Voltage Capture System observing mode. Sources of potential error in the reconstruction of the high time resolution data are identified and quantified, with the $S/N$ loss induced by the back-to-back system not exceeding $-0.65\,$ dB for typical noise-dominated samples. The system is further verified by observing three pulsars with known structure on microsecond timescales.
P.p. Vaidyanathan - One of the best experts on this subject based on the ideXlab platform.
-
analog Filter banks for sampling discretization polyphase form and role in compressive sensing
2013 IEEE Digital Signal Processing and Signal Processing Education Meeting (DSP SPE), 2013Co-Authors: P.p. VaidyanathanAbstract:Continuous-time signals arising in many applications can often be modeled as the outputs of analog Synthesis-Filter banks driven by discrete-time inputs di(n). Such a signal x(t) has a finite innovations rate, although it may not be bandlimited in general. In some applications it is necessary to sample such signals after Filtering with an analog sampling-Filter-bank, to recover the driving signals di(n): This sampling Filter bank is in general not unique, and the theory and design techniques for such analog Filter banks are not as well developed as the large body of literature on digital Filter banks. In this paper we show that the theoretical as well as design and implementation issues can be formulated in terms of digital Filter banks, by taking advantage of the finite innovations rate of x(t): The rich body of knowledge on digital Filter banks and polyphase forms can therefore be utilized and furthermore the optimization of the sampling Filter bank can be done on a more convenient platform. Applications of this development in the context of compressive sensing are also elaborated.
-
linear phase cosine modulated maximally decimated Filter banks with perfect reconstruction
IEEE Transactions on Signal Processing, 1995Co-Authors: Yuanpei Lin, P.p. VaidyanathanAbstract:We propose a novel way to design maximally decimated FIR cosine modulated Filter banks, in which each analysis and Synthesis Filter has a linear phase. The system can be designed to have either the approximate reconstruction property (pseudo-QMF system) or perfect reconstruction property (PR system). In the PR case, the system is a paraunitary Filter bank. As in earlier work on cosine modulated systems, all the analysis Filters come from an FIR prototype Filter. However, unlike in any of the previous designs, all but two of the analysis Filters have a total bandwidth of 2/spl pi//M rather than /spl pi//M (where 2M is the number of channels in our notation). A simple interpretation is possible in terms of the complex (hypothetical) analytic signal corresponding to each bandpass subband. The coding gain of the new system is comparable with that of a traditional M-channel system (rather than a 2M-channel system). This is primarily because there are typically two bandpass Filters with the same passband support. Correspondingly, the cost of the system (in terms of complexity of implementation) is also comparable with that of an M-channel system. We also demonstrate that very good attenuation characteristics can be obtained with the new system.
-
linear phase cosine modulated maximally decimated Filter banks with perfect reconstruction
International Symposium on Circuits and Systems, 1994Co-Authors: Yuanpei Lin, P.p. VaidyanathanAbstract:In this paper a new type of maximally decimated FIR cosine modulated Filter bank is proposed. Each analysis and Synthesis Filter in this Filter bank has linear phase. We can design the system to have approximate reconstruction property (pseudo-QMF system) or perfect reconstruction property (PR system). The Filter bank is paraunitary in the PR case. Although there are 2M channels in the new system, the cost (in terms of design and implementation complexity) is comparable to that of an M channel system. Correspondingly, the coding gain of the new system is also comparable to that of a traditional M channel system (rather than a 2M channel system). Examples will be given to demonstrate that very good attenuation characteristics can be obtained with the new system. >
-
Vector space framework for unification of one- and multidimensional Filter bank theory
IEEE Transactions on Signal Processing, 1994Co-Authors: Tsuhan Chen, P.p. VaidyanathanAbstract:A number of results in Filter bank theory can be viewed using vector space notations. This simplifies the proofs of many important results. In this paper, we first introduce the framework of vector space, and then use this framework to derive some known and some new Filter bank results as well. For example, the relation among the Hermitian image property, orthonormality, and the perfect reconstruction (PR) property is well-known for the case of one-dimensional (1-D) analysis/Synthesis Filter banks. We can prove the same result in a more general vector space setting. This vector space framework has the advantage that even the most general Filter banks, namely, multidimensional nonuniform Filter banks with rational decimation matrices, become a special case. Many results in 1-D Filter bank theory are hence extended to the multidimensional case, with some algebraic manipulations of integer matrices. Some examples are: the equivalence of biorthonormality and the PR property, the interchangeability of analysis and Synthesis Filters, the connection between analysis/Synthesis Filter banks and Synthesis/analysis transmultiplexers, etc. Furthermore, we obtain the subband convolution scheme by starting from the generalized Parseval's relation in vector space. Several theoretical results of wavelet transform can also be derived using this framework. In particular, we derive the wavelet convolution theorem.
