Mathematica's highly optimized filtering capabilities provide a wide range of linear and modern nonlinear local filters, as well as a variety of nonlocal filters, which can be applied to arbitrary arrays of data and images.
GaussianFilter — Gaussian and Gaussian derivatives filtering of images and arrays
ListConvolve,
ListCorrelate — convolve, correlate with any kernel
DerivativeFilter — general-order derivative filter
CellularAutomaton — general cellular automaton
