1. A computer implemented method comprising: partitioning a first portion of a non-separable finite impulse response (FIR) filter into a plurality of constant response sub-filters, wherein each constant response sub-filter has a rectangular aperture; partitioning a second portion of the non-separable FIR filter into one or more satellite sub-filters; setting one or more samples for the non-separable FIR filter to zero to obtain an arbitrary shape for an aperture of the non-separable FIR filter, wherein the arbitrary shape includes at least one of a circular shape and an elliptical shape; and using the plurality of constant response sub-filters and the one or more satellite sub-filters to blur an image.