State-space formulation of frequency transformation for 2-D digital filters

This letter proposes frequency transformation for two-dimensional (2-D) digital filters in terms of the state-space equations. In order to derive the 2-D state-space formulation of the frequency transformation, we extend Mullis and Roberts' state-space formulation of one-dimensional frequency transformation to 2-D case. The proposed frequency transformation is very suitable for state-space analysis of the transformed filters since the resultant formulation consists of simple algebraic operations such as matrix addition, multiplication, inverse and so on. It can be easily implemented in MATLAB without any complicated algorithm.