1. An image processing apparatus comprising: an image input unit that receives a digital image as an input image; a controller that obtains a designated output size; a first image expansion/reduction unit that employs a first method to change a size of an image; a second image expansion/reduction unit that employs a second method to change a size of an image, the second method changing the size of the image at a higher speed than the first method; and an image restoration unit that performs an image restoration process including a color correction process, a sharpening process and a noise reduction process for an image; wherein [A] if any of (i) a total number of pixels obtained by multiplying a number of pixels of an output image having the designated output size in a row direction and a number of pixels of the output image having the designated output size in a column direction, (ii) both of the numbers of pixels of the output image having the designated output size in the row and column directions, (iii) the number of pixels of the output image having the designated output size in the row direction and (iv) the number of pixels of the output image having the designated output size in the column direction is larger than a predetermined value, the controller selects the first image expansion/reduction unit and controls the first image expansion/reduction unit and the image restoration unit so that the first method and the image restoration process for the digital image to generate the output image having the designated output size is performed, and [B] in the other cases, the controller selects the second image expansion/reduction unit and controls the second image expansion/reduction unit so that the second method and the image restoration process is performed while inhibiting at least one of the sharpening process and the noise reduction process, to generate the output image having the designated output size, the first image expansion/reduction unit performs an expansion or reduction process in a first direction of a digital image and the expansion or reduction process in a second direction perpendicular to the first direction independently, and if the controller selects the first image expansion/reduction unit, the controller controls an order of (i) the expansion or reduction process in the first direction, (ii) the expansion or reduction process in the second direction and (iii) the image restoration process so that a number of pixels of the image for which the image restoration process is performed is minimized.