An image interpolation apparatus receives an image signal in the frequency domain. The image signal is supplied to a filter circuit. The output of the filter circuit is transformed by a two-dimensional fourier transformation circuit into a filtered image signal in the spatial domain. The filtered image...http://www.google.co.uk/patents/US5301266?utm_source=gb-gplus-sharePatent US5301266 - Apparatus to improve image enlargement or reduction by interpolation
