In a multifunction product including a plurality of input sources and a plurality of output destinations corresponding to the function thereof, there are an input document class that fits an input document input from the input source to a common format regardless of the input sources and manages the input document, a user document class that obtains user images of a predetermined size to be processed from the input document and manages the user document formed of the obtained user images, and an output document class that uses the output image created from the user images constituting the user document to create an output document reshaped in a format to be output to the output destination and output the output document.