A technique of processing images previously-formed on first and second opposite sides of a document is disclosed. The technique includes: reading the images on the document at a reading position by scan; transporting the document such that the first side is moved facing the reading position, and, after the first side is read, the second side is moved facing the reading position; and controlling at least one of a start-of-reading timing of the first side and a start-of-reading timing of the second side, such that a relationship between the start-of-reading timing of the first side and the start-of-reading timing of the second side varies, depending on whether or not an extension direction of a binding edge along which the document is to be bound is parallel to a document orientation in which a length of the document is oriented with respect to a transport direction of the document being transported.