Two dimensional filtering using fermat number transforms

Two dimensional convolution computed using minicomputers is very time-consuming using Fourier Transform techniques because of the number of complex multiplications required. It has been shown that by employing Fermat Number Transforms a hardware butterfly unit becomes relatively simple to implement and significantly increases the speed of the calculation. Such a hardware unit, suitable for interfacing to a minicomputer, is briefly described. An algorithm is given which removes the need for a matrix transposition. This algorithm is useful on small disc based computers which cannot store the complete input matrix in main memory since a matrix transposition is a time-consuming operation.