Edge directional interpolation for image upscaling with temporarily interpolated pixels

The proposed image upscaling technique uses an edge directional kernel during the interpolation process to improve the edge quality of upscaled images. Especially, the kernel is applied to a set of temporarily interpolated pixels (TIPs), which are distributed symmetrically around the target pixel. When images are upscaled by an arbitrary magnification factor, the arrangement of input data is often asymmetric with respect to the target pixel. This asymmetric arrangement makes it more complicated to perform edge directional interpolation (EDI). In the proposed method, the asymmetric interpolation lattice problems are simplified as symmetric ones by using the symmetrically arranged set of TIPs. Therefore, the EDI process is performed simply within this symmetric grid, even in cases of arbitrary ratio enlargement.