1. An image processing apparatus comprising: an extractor that receives sheet image data that is generated by reading an image on a medical record sheet onto which basic medical information and encoded information of the basic medical information are printed, and extracts, from the sheet image data, information image data representing a portion where the basic medical information is printed; an image generator that generates reference image data representing the basic medical information, based on the encoded information represented in the sheet image data; and a detector that detects a correction that is to be performed on the basic medical information printed on the medical record sheet, based on a difference between the information image data and the reference image data.