An image processing unit includes a first image processing unit that processes image data from a reading unit and a second image processing unit that processes image data from either one of the first image processing unit and a storing unit. A control unit determines a processing to be performed on the image data by the second image processing unit depending on a result of a processing performed on the image data by the first image processing unit, and selects an image processing route depending on a processing to be performed on the image data by the second image processing unit.