INTERPOLATION DEVICE, PROCESS AND RECORDING MEDIUM ON WHICH INTERPOLATION PROCESSING PROGRAM IS RECORDED

An interpolation device performs interpolation of an image in which grid points that output a predetermined color and empty grid points that do not output the predetermined color are arrayed in a checkered configuration. A recording medium stores an image interpolation processing program. A first similarity calculator calculates a first vertical direction similarity and a first horizontal direction similarity. A second similarity calculator calculates a second vertical direction similarity and a second horizontal direction similarity. A similarity calculator determines the similarity in the vertical direction of an empty grid point based on the first vertical similarity and the second horizontal similarity and determines the similarity in the horizontal direction of the empty grid point based on the first horizontal similarity and the second horizontal similarity. An interpolation amount calculator calculates an interpolation amount, by selecting the pixel output of grid point(s) positioned in a direction with a strong similarity, or by weight-adding the pixel outputs of the grid points positioned in the vertical direction and the horizontal direction, according to the similarities that are determined.