Page image correction device, and recording medium

Patent metadata

Field	Value
Publication number	US-9485389-B2
Application number	US-201514843015-A
Country	US
Kind code	B2
Filing date	Sep 2, 2015
Priority date	Sep 12, 2014
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

A page image correction device includes: an acquisition unit that acquires a page image of each page of a plurality of pages from a book, the book being successively imaged in a thickness direction thereof; and a processor configured to: 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 the first prescribed page as compared to when the book is opened to the second prescribed page; and correct, in accordance with the amount of change in the thickness of the book, page images of pages between the first prescribed page and the second prescribed page.

First claim

What is claimed is:

1. A page image correction device, comprising:
an acquisition unit that acquires a page image of each page of a plurality of pages from a book, the book being successively imaged in a thickness direction thereof; and
a processor configured to:
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.

2. 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.

3. The page image correction device according to claim 2 , wherein the processor determines two ends of the top reference line and two ends of the bottom reference line as said four reference points, respectively.

4. The page image correction device according to claim 2 , wherein the processor estimates the amount of the vertical deflection in accordance with the length in the seam direction of the divided regions.

5. The page image correction device according to claim 4 , wherein the processor estimates the amount of the vertical deflection of the respective divided regions using formula
dz ( i )= k·{H ( i )− H ( i− 1)},

where i is the corresponding divided region, dz(i) is the amount of the vertical deflection of the i th divided region, k is a constant coefficient, H(i) is the length in the seam direction of the i th divided region, and H(i−1) is the length in the seam direction of the i−1 th divided region.

6. The page image correction device according to claim 5 , wherein k is determined such that an aspect ratio of the combined page image is approximately equal to an aspect ratio of the corresponding page.

7. The page image correction device according to claim 2 , wherein the processor combines the n-number of divided regions such that said divided regions are linked in the same arrangement order in the width direction as during division of said divided regions.

8. The page image correction device according to claim 2 , wherein the processor corrects the quadrilateral distortions in accordance with a projection matrix that projects the four reference points to four target points that form the prescribed quadrilateral shape.

9. The page image correction device according to claim 8 ,
wherein the processor derives a perturbation amount ΔA that represents a change in the projection matrix for each single page change in accordance with the projection matrices of two pages that are separated from each other; regards one of said two pages as a reference page; and derives a projection matrix of each page between said two pages by perturbing the projection matrix of the reference page by the perturbation amount ΔA in an amount corresponding to a number of pages from the reference page.

10. The page image correction device according to claim 9 , wherein said two pages are both left pages or are both right pages.

11. The page image correction device according to claim 2 ,
wherein the processor derives a perturbation amount ΔUL that represents a change in the quadrilateral distortion corrected top reference line for each single page change in accordance with the respective quadrilateral distortion corrected top reference lines of two pages that are separated from each other,
wherein the processor derives a perturbation amount ΔDL that represents a change in the quadrilateral distortion corrected bottom reference line for each single page change in accordance with the respective quadrilateral distortion corrected bottom reference lines of said two pages,
wherein the processor regards one of said two pages as a reference page; derives the quadrilateral distortion corrected top reference line of each page between said two pages by perturbing the quadrilateral distortion corrected top reference line of the reference page by the perturbation amount ΔUL in an amount corresponding to a number of pages from the reference page; and derives the quadrilateral distortion corrected bottom reference line of each page between said two pages by perturbing the quadrilateral distortion corrected bottom reference line of the reference page by the perturbation amount ΔDL in an amount corresponding to the number of pages from the reference page.

12. The page image correction device according to claim 11 , wherein said two pages are both left pages or are both right pages.

13. The page image correction device according to claim 2 ,
wherein the processor locates a line at the top of the page image that is supposed to be a straight line if the page image does not contain any distortion, and determines said line as the top reference line, and
wherein the processor locates a line at the bottom of the page image that is supposed to be a straight line if the page image does not contain any distortion, and determines said line as the bottom reference line.

14. The page image correction device according to claim 13 , wherein, if a pattern that is a candidate for the top or bottom reference line does not uniquely define a straight line having connected dots, the processor calculates a line having connected dots that go through a center of said pattern.

15. The page image correction device according to claim 13 , wherein, if said determined top reference line or said bottom reference line does not reach from one end of a page to another end in a left-right direction, the processor extends said top reference line or said bottom reference line so as to reach from said one end of the pag

Assignees

• Casio Computer Co Ltd

Inventors

• Nimura Ryo

Classifications

• H04N1/00726 Primary

  Other properties of the sheet, e.g. curvature or reflectivity · CPC title

• H04N1/387

  Composing, repositioning or otherwise {geometrically} modifying originals · CPC title

• H04N2201/0081

  Image reader (H04N2201/0091 - H04N2201/0094 take precedence) · CPC title

• H04N1/409 Primary

  Edge or detail enhancement; Noise or error suppression · CPC title

• H04N1/00716

  Thickness · CPC title