EDGE GENERATION METHOD, EDGE GENERATION DEVICE, MEDIUM RECORDING EDGE GENERATION PROGRAM, AND IMAGE PROCESSING METHOD

A direction of an intended edge is determined, and a position of the intended edge is corrected to a position that brings a direction that connects a position of the intended edge and a position of an adjacent edge closer to the determined direction of the intended edge, and edge information representative of an area of the edge of an enlarged image is generated by using the corrected position of the edge. Gradation data before and after filtering are synthesized at a rate corresponding to a feature quantity representative of the amount of pixels within a predetermined color area. The gradation data of the plural pixels within a predetermined region including the position of the intended edge to be sharpened among the interpolated gradation data of the respective pixels on the interpolated image is sharpened at a degree corresponding to the number of pixels of the uninterpolated image.