2-D IFIR structures using generalized factorable filters

The extension of the idea of Interpolated FIR filters to the two-dimensional case is presented. Such systems allow for lower computational weight, in terms of number of elementary operations per input sample. We have considered 2-D IFIR filters with parallelogram-shaped spectral support. To design the filters in the two stages, we have used a technique recently developed by Chen and Vaidyanathan. The resulting filters belong to the class of Generalized Factorable filters, for which an efficient implementation exists. An interesting problem peculiar to the multidimensional case is the choice of the sublattice which represents the definition support of the first-stage filter. We present a strategy for choosing (given the spectral support of the desired frequency response) the optimal sublattice, and to design the second-stage (interpolator) filter in order to achieve low overall computational complexity