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A simple method for designing quadrature mirror filter banks via quadratic constrained optimisation

This paper proposes a simple algorithm for the design of a two-channel linear phase quadrature mirror filter (QMF) bank. The design problem is formulated as a quadratic constrained least square minimisation that optimises the performance of a prototype filter (PF) and distortion transfer function of filter bank at quadrature frequency. A new method is developed for the design of a low pass prototype filter for QMF banks. For solving the given optimisation problem, a sequential quadratic programming (SQP) technique is used. Numerical examples and comparisons with several existing methods are included to show the performances and the effectiveness of the proposed method. An application of this method is considered in the area of subband coding of the images.