The image input part (3) in an authoring device (1) reads a plurality of pages of a paper publication and creates images of the pages. In the border eliminating part (9) of the authoring device (1), a common area extraction part (15) extracts the area common to all of the images of the pages. The layouts with respect to at least either text or drawings in this common area of the images resemble one another. The non common-area replacement part (19) replaces the color of the portion outside the common area of the images with the background color of the common area, so as to remove the border outside the common area of each of the images. An image output part (5) in the authoring device (1) outputs the data of the post-replacement images of all of the pages of the paper publication as the contents of an electronic publication.