
Two dimensional filters have seen substantial development effort due to their importance and large applicability across several domains. In the 2D case the situation is quite different from 1D case, because the multidimensional polynomials can't be factored in generally. This means that an arbitrary transfer function can generally not be manipulated into a form required by a particular implementation. The inputoutput relationship of a 2D IIR filter obeys a constantcoefficient linear partial difference equation from which the value of an output sample can be computed using the input samples and previously computed output samples. Because the values of the output samples are fed back, the 2D filter, like its 1D counterpart, can be unstable. [More Information] 