Method for designing nearly circularly symmetric descreening filters that can be efficiently implemented in VLIW (very long instruction word) media processors

A method is disclosed for designing two separable filters, LPP & HPP, that approximates the circularly symmetric frequency response achievable using a non-separable filter. The method selects a cut-off frequency and designs a 1-D low pass filter. Next, the method obtains a low pass 2-D filter and generates a 2-D contour plot therefor. The method designs a 1-D high pass filter and obtains a 2-D high pass filter and a 2-D contour plot therefor. A 2-D filter is generated having the dimensions of the 2-D high pass filter with the only non-zero entry of value 1 located at the center. A matrix is created by subtracting the 2-D high pass filter from the 2-D filter. The low pass 2-D filter is convolved with the matrix to obtain an approximation to a desired circular symmetry.