Edge-and-corner-directed interpolation

This paper proposes an edge-and-corner-directed interpolation for image rescaling. While edge-only-directed interpolation reconstructs edges very well over traditional image interpolation methods such as bi-linear or bi-cubic, it often produces critical artifacts, if there is a corner where two or more edges sharply join. In our method, we first try to find a global linear edge direction in a given n * n window. If it fails, we divide the window into 4 sub-windows and try to find an edge direction in each sub-window to determine whether corner exists. The results show that new interpolation preserves the crispiness of edges and improves the overall perceptual image quality as well.