Page image correction device, and recording medium

A page image correction device, comprising:

• a page image acquisition unit that acquires a page image of each page of a plurality of pages from a book;
• and
• a processor configured to, with respect to at least some of the plurality of pages from the book:
• receive data representing the page image;
• acquire a top reference line extending in a page width direction at a top of the page image, and a bottom reference line extending in the page width direction at a bottom of the page image from the received data representing the page image;
• determine four reference points on the page image based on said top reference line and said bottom reference line;
• correct quadrilateral distortions on the page image using said four reference points as references so that said reference points, after the correction, form a prescribed quadrilateral shape;
• virtually divide the page image, the quadrilateral distortions of which have been corrected, into an n-number of substantially rectangular divided regions, the substantially rectangular divided regions extending along a seam direction of the book between a quadrilateral distortion corrected top reference line and a quadrilateral distortion corrected bottom reference line and being arranged in a width direction that is perpendicular to said seam direction;
• correct a vertical length in the seam direction of each of the divided regions so that the vertical length of each of the divided regions becomes the same;
• estimate an amount of vertical deflection for each of the divided regions, the vertical length of which has been corrected;
• correct a horizontal length in the width direction of each of the divided regions on a basis of the amount of the vertical deflection that has been estimated;
• and
• combine the n-number of the divided regions, the vertical and horizontal lengths of which have been corrected, thereby creating data representing a combined and corrected page image.

A non-transitory computer-readable storage medium having stored therein a program executable by a processor that controls a page image correction device, said program causing said processor to perform the following:

• acquire a page image of each page of a plurality of pages from a book, the book being successively imaged in a thickness direction thereof;
• derive, in accordance with a page image of a first prescribed page and a page image of a second prescribed page differing from the first prescribed page, an amount of change in a thickness of the book when the book is opened to said first prescribed page as compared to when the book is opened to said second prescribed page;
• and
• correct, in accordance with said amount of change in the thickness of the book, page images of pages between the first prescribed page and the second prescribed page.