Efficient image interpolation scheme using hybrid IIR Nyquist filters

This paper presents efficient filtering algorithms for the interpolation of sequences using IIR filters. Of the suggested filters, the most efficient in terms of computational complexity consists of a very simple allpass IIR filter in parallel with a pure delay. The nonlinear phase distortions of IIR filters, particularly severe in image processing, are avoided by a zero-phase implementation obtained by a combination of causal and anticausal filters. The proposed approach is more efficient for image zooming applications than other methods and yields visually satisfactory results for most gray-scale images.