Universal spatial up-scaler with nonlinear edge enhancement

Spatial image resizing is an important issue for pixel oriented displays with variable input formats. A known example is a scaling factor of two for up-scaling from Standard Definition (SD) to High Definition (HD) format. Nonlinear image processing introduce higher harmonics to enhance the image sharpness. However it may create annoying alias artefacts, too. We investigated an up-scaler for rational factors with nonlinear detail enhancement. The method for scaling is based on economic diamond shaped filters. The additional available frequency space is filled with higher harmonic frequencies created from the detail signal by an improved approach for nonlinear signal processing. The bandwidth of higher harmonics is limited to the output Nyquist frequency in order to prevent aliasing.