 In this section, we examine the technique for designing 2-D IIR filters based on minimizing error functionals in the frequency domain.The mean-squared error is given as

formula_336

The below function formula_337 is the measure of difference between two complex functions - the desired response formula_338 and the actual response formula_90.Generally, we can define a complex function formula_340 of formula_341 to approximate the desired response formula_342.