Local dip filtering with directional Laplacians

Local dip filters attenuate or enhance features with a specified dip that may vary
for each image sample. Because these multi-dimensional filters change with each
sample, they should have a small number of coefficients that can be computed
efficiently from local dips. They should handle features that are vertical as
well as horizontal. They should have efficient and stable inverses that facilitate
the design and application of more discriminate notch filters. Local dip filters
constructed from approximations to directional Laplacians have these properties
and are easily implemented in any number of dimensions.