New approach for designing recursive 2-D variable digital filters

This paper proposes an efficient technique for designing recursive two-dimensional (2-D) variable digital filters with arbitrary magnitude characteristics. The technique is based on the decomposition of the given 2-D variable magnitude specifications. Using this technique, we can obtain a 2-D variable digital filter by simply designing a set of 2-D constant filters and approximating a set of l-D polynomials. Consequently, the original difficult 2-D variable filter design problem can be significantly simplified