1. An image inspection apparatus that inspects a read image generated by reading a printed image formed on a recording sheet, the apparatus comprising a processor configured to: obtain a preprint inspection image that reflects an image previously formed on the recording sheet; obtain an output target inspection image generated based on an image formed on the recording sheet having the preprint image previously formed, the preprint inspection image being combined with the output target inspection image to generate an inspection image; determine whether a portion of the read image being read from the printed image reaches an inspection unit of data subjected for inspection; correct the size of at least one of the read image or the inspection image using a magnification ratio to match the sizes of the read image and the inspection image for the read portion of the read image when the read portion reaches the inspection unit, the magnification ratio being previously obtained based on the preprint inspection image; and compare the read portion of the read image with a corresponding portion of the master image to inspect the read portion of the read image, wherein the processor performs determining, correcting, and comparing until a predetermined number of pages of the read image are inspected using the inspection image.