Image interpolation based on median-type filters

Image interpolation based on median-type filters is investigated. We study this problem for two decimation schemes that are most commonly used in practice: (1) quincunx lattice and (2) rectangular lattice. For each decimation lattice, we propose a number of interpolation structures that are based on some median or finite impulse response (FIR)-median hybrid filters. Extensive simulations show that the proposed median-based interpolators outperform significantly as compared with linear schemes. To further verify the effectiveness of these medianbased interpolators, we compare them with multilayer neural networks designed through a training process, and still show a preference for the median-based interpolators. As an application, they are used in an interpolative Joint Photographic Experts Group (JPEG) coding scheme to suppress blocking artifacts at very low bit rates.