Image processing apparatus configured to encode identification information about a package for delivery

An image processing apparatus includes a display, an input device, and a processor configured to accept, through the input device, a user input of identification information about a package for delivery, acquire information about a plurality of document types used in a delivery service, generate a screen displayed on the display, the screen showing a preview of a print image for each of the document types, upon selection of a previewed print image, encode the identification information into a code, and output the selected print image together with the code for printing. The previewed print image includes a signature field and a code field in which the code is to be printed.