Designing a separate filter for each patch

Recall the prediction-error filter subroutine find_pef() . Given a data plane, this subroutine finds a filter that tends to whiten the spectrum of that data plane. The output is white residual. Now suppose we have a data plane where the dip spectrum is changing from place to place. Here it is natural to apply subroutine find_pef() in local patches. This is done by subroutine find_lopef(). The output of this subroutine is an array of helix-type filters, which can be used, for example, in a local convolution operator loconvol . lopeflocal PEF We notice that when a patch has fewer regression equations than the filter has coefficients, then the filter is taken to be that of the previous patch. loconvollocal convolution