Why filter recursively in two dimensions?
R.E. Twogood, Michael P. Ekstrom · 2005
The relative advantages of 2-D recursive digital filters over their nonrecursive counterparts are discussed. A design example illustrates the ability of 2-D recursive filters to yield excellent responses with far fewer coefficients than nonrecursive filters require. This difficulty is seen to be partially overcome by using nonrecursive filters with very efficient implementations.