Derivation of a novel state-space formulation of 2-D frequency transformation by LFT techniques

This note derives a novel alternative state-space formulation of 2D frequency transformation for 2D digital filters by utilizing linear fractional transformation (LFT) techniques. It turns out that the obtained new state-space formulation is much simpler than the existing result. Moreover, all the known 1D and 2D formulations can be unified by the proposed formulation as special cases. Numerical examples are given to illustrate the effectiveness of the proposed formulation.