As illustrated in FIG. 5, in a case in which generation of a temporary reference image and oversampling are not performed with respect to an editing process of rotating an image with an arbitrary angle other than 90 degrees (45 degrees in FIG. 5), aliasing and blurring occur because the sampling direction deviates from the sampling direction of the original digital image. Similarly, in a case in which generation of a temporary reference image and oversampling are not performed with respect to an editing process of shifting an image by 0.5 pixel, blurring occurs because of not being shift-invariant.

Meanwhile, in the processing by the image processing apparatus 1 according to the present embodiment, after a temporary reference image with an appropriate resolution of approximately √2 times or twice is generated respectively with respect to a rotation operation in FIG. 3 and a shifting operation by 0.5 pixel in FIG. 4, and oversampling is performed at an appropriate rate of approximately two to three times higher than the sampling rate for the resolution of the temporary reference image, the temporary reference image is converted into a digital image with the target resolution. Accordingly, at the time of oversampling, it becomes possible to avoid aliasing caused by misalignment in the sampling direction due to rotation, and reduce blurring generated by a calculation process using pixel values of peripheral pixels, thereby enabling to suppress deterioration.