Ten lectures on wavelets
Multirate systems and filter banks
Multirate systems and filter banks
Wavelets and subband coding
Role of anticausal inverses in multirate filter-banks .I.System-theoretic fundamentals
IEEE Transactions on Signal Processing
Two-channel IIR QMF banks with approximately linear-phase analysisand synthesis filters
IEEE Transactions on Signal Processing
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A general family of mixed IIR/FIR two-channel QMF filter banks (FB) with near perfect reconstruction (NPR) is presented. The design method is general in the sense that all possible distortions (aliasing, imaging, amplitude and phase distortions) can be simultaneously and arbitrarily minimised. In addition, variants of the method allow for a total removal of aliasing, imaging and/or phase distortions. The perfect or approximate linear phase property of analysis and synthesis filters could be easily incorporated during the design procedure. The method is based on a simple algorithm, also included, to approximate unstable all-pole filters with FIR filters. The resulting FB is efficient because a polyphase implementation is possible and delay is low compared to conventional FIR filter banks; also, the proposed approach offers a trade-off between savings of delay and/or computational cost and accuracy of FB reconstruction. It is also shown that some well-known two-channel FIR and IIR FBs are particular classes of the proposed one. Moreover, the filter bank has a natural two-dimensional extension resulting in efficient diamond-shaped frequency support NPR FBs. Examples illustrating these claims and showing an application to image compression are included.