A method to accelerate the design of 2-D circularly symmetric finite impulse response (FIR) filters is presented. This method utilizes the circular symmetry property and computes the elements of the impulse response using only the elements located on a half-axis in the space domain, i.e., h(m,0). h(m,n) can be computed using B-spline and piecewise Lagrange interpolation on h(m,0). When used in conjunction with nonlinear optimization, this method results in considerable reduction of execution time and lower sensitivity to the initial vector. This characteristic can be useful in higher-order filters where finding a suitable initial vector for a better local optimum becomes more difficult.
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