“…Therefore, the variable 2-D transfer function (2) can be expressed as (14) whose frequency response is given by (15) where Defining the complex-valued error (16) our objective here is to find the optimal coefficient matrices and such that the total weighted squared-error (17) is minimized, where is a nonnegative fourdimensional weighting function. In this paper, we assume that the weighting function is separable, i.e., (18) and the 1-D functions are piecewise constant. For example, for the frequencies in the range we first divide the interval into the union of several small intervals (sub-intervals) as (19) where Then, the sub-weighting function is chosen to be constant in each sub-interval, i.e., for (20) where are constants for In addition, we assume that the sub-weighting function for is symmetric with respect to Likely, is defined as for (21) where As for the sub-weighting function the interval [0, 1] is divided into the union of sub-intervals as (22) where For each sub-interval, the corresponding sub-weighting function is constant, i.e., for…”