A paper size that can be created using an application software program (hereinafter abbreviated as an application) operating on a computer often has a maximum value, and maximum values differ from application to application. Thus, in order to obtain a printout of a size larger than the maximum paper size of an application, cumbersome operations have been needed such as calculating a paper size (including an aspect ratio) while taking the maximum paper size of the application into consideration, setting the paper size in the application, and calculating and setting an enlargement ratio of a printer driver.In the present invention, in a plug-in of a general-purpose application, a user is only required to specify the size of a printout to be output in order to calculate a paper size that has the same aspect ratio as an output size that is within the maximum paper size of the application and to set the paper size in the printer driver and the application. Thereby, the foregoing problems are overcome.