On the synthesis of digital two dimensional filters based on FIR filters approximation

We use the two-dimensional windowing method to design a digital 2D-FIR filter with linear phase, circularly symmetric with respect to the origin of the frequency plane. To get an economical filter with high information efficiency, an interesting way is applying the balanced realization method to this full-order filter. As a result, a linear phase IIR filter is obtained whose frequency response is very close to that of the initial filter.