A storing unit stores document information received from an OS through an AP processing unit. A character size information extracting unit extracts representation character size information that represents a maximum size of characters whose accumulated number reaches a predetermined ratio of a total number of characters included in the document information. A resolution information extracting unit extracts resolution information. A page number deciding unit decides an arranged page number serving as the number of logical pages from the representation character size information and the resolution information. A page arranging unit converts the document information stored in the storing unit into the logical pages and arranges them to a physical page based on the logical pages and the arranged page number. The inputted document information divided into a plurality of logical pages is converted into image information consisting of physical pages of the number smaller than the number of logical pages.