When the size output for an image is equal to or smaller than a predetermined value (e.g., index printing), a printing apparatus performs an image expansion/reduction process by using an interpolation method whereby high speed processing is enabled while an inferior image quality is provided, or when the output size is greater than a predetermined value (e.g., the normal printing of a single sheet), employs an interpolation method for a high quality image to perform the expansion/reduction. Further, when the output image size is equal to or smaller than the predetermined value, the printing apparatus 1 skips the noise reduction process and the sharpening process to increase the processing speed.