Methods and Systems for Correcting a Document Image

• US 20140292802A1
• Filed: 03/26/2013
• Published: 10/02/2014
• Est. Priority Date: 03/26/2013
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Chen, Lawrence Shao-hsien
• Granted Patent: US 9,317,893 B2
• Time in Patent Office: Days
• US Class Current: 345/609
• CPC Class Codes: G06T 3/06 Topological mapping of higher dimensional structures onto lower dimensional surfaces

Abstract

Aspects of the present invention relate to methods and systems for fitting a mesh to an image of a document page and correcting a distortion in the image of the document page using the mesh. A rectangular-form mesh may be overlaid on a displayed document image. Corner points in the rectangular-form mesh may be moved to coincide with corner points of a document page in the displayed document image, and a corner-aligned mesh may be overlaid on the displayed document image. A cubic Bezier curve may be fit to the top edge of the document page, a cubic Bezier curve may be fit to the bottom edge of the document page and an edge-aligned mesh may be overlaid on the displayed image. An inverse projective transformation may be applied to the patches of the mesh to correct the distortion in the image of the document page.

Claims

1. A method for fitting a mesh to an image of a document page, said method comprising:

displaying a document image on a touch-enabled-device display;

overlaying a rectangular-form mesh on said displayed document image;

receiving a plurality of corner points;

overlaying a corner-aligned mesh on said displayed document image;

receiving a touch displacement comprising an initial touch point and a final touch point;

determining a nearest intermediate control point to said initial touch point;

adjusting an edge curve associated with said nearest intermediate control point based on said touch displacement; and

generating an edge-aligned mesh based on said adjusted edge curve.

2. A method as described in claim 1, wherein said corner-aligned mesh comprises a top edge and a bottom edge, wherein said top edge is a first cubic Bezier curve and said bottom edge is a second cubic Bezier curve.

3. A method as described in claim 2, wherein said edge curve is associated with one of said top edge and said bottom edge.

4. A method as described in claim 1, wherein receiving a first corner point in said plurality of corner points comprises:

receiving a touch gesture in a gesture processor; and

determining if said touch gesture is a drag gesture associated with a corner of said rectangular-form mesh.

5. A method as described in claim 4, wherein said determining if said touch gesture is a drag gesture associated with a corner of said rectangular-form mesh comprises comparing an initial point associated with said touch gesture with a location of a vertex of said rectangular-form mesh.

6. A method as described in claim 4, wherein said first corner point is associated with a final point associated with said drag gesture.

7. A method as described in claim 1, wherein said adjusting an edge curve associated with said nearest intermediate control point comprises:

determining a touch-displacement distance;

determining a touch-displacement direction; and

adjusting a cubic Bezier curve associated with said edge curve by moving said nearest intermediate control point a distance corresponding to said touch-displacement distance in a direction corresponding to said touch-displacement direction.

8. A method as described in claim 1 further comprising correcting a portion of said document image corresponding to said edge-aligned mesh.

9. A method as described in claim 8, wherein said correcting comprises an inverse projective transformation.

10. A method as described in claim 8, further comprising subdividing any patch in said edge-aligned mesh wherein a surface curvature associated with said any patch exceeds a first threshold.

11. A method as described in claim 1 further comprising overlaying an intermediate corner-aligned mesh on said displayed document image in response to receiving each of said corner points in said plurality of corner points.

12. A method for correcting an image of a document page, said method comprising:

displaying a document image on a touch-enabled-device display;

overlaying a rectangular-form mesh on said displayed document image;

receiving a plurality of corner points;

overlaying a corner-aligned mesh on said displayed document image;

receiving a touch displacement comprising an initial touch point and a final touch point;

determining a nearest intermediate control point to said initial touch point;

adjusting an edge curve associated with said nearest intermediate control point based on said touch displacement;

generating an edge-aligned mesh based on said adjusted edge curve; and

correcting a portion of said document image corresponding to said edge-aligned mesh.

13. A method as described in claim 12, wherein said corner-aligned mesh comprises a top edge and a bottom edge, wherein said top edge is a first cubic Bezier curve and said bottom edge is a second cubic Bezier curve.

14. A method as described in claim 13, wherein said edge curve is associated with one of said top edge and said bottom edge.

15. A method as described in claim 12, wherein receiving a first corner point in said plurality of corner points comprises:

receiving a touch gesture in a gesture processor; and

determining if said touch gesture is a drag gesture associated with a corner of said rectangular-form mesh.

16. A method as described in claim 15, wherein said determining if said touch gesture is a drag gesture associated with a corner of said rectangular-form mesh comprises comparing an initial point associated with said touch gesture with a location of a vertex of said rectangular-form mesh.

17. A method as described in claim 15, wherein said first corner point is associated with a final point associated with said drag gesture.

18. A method as described in claim 12, wherein said adjusting an edge curve associated with said nearest intermediate control point comprises:

determining a touch-displacement distance;

determining a touch-displacement direction; and

adjusting a cubic Bezier curve associated with said edge curve by moving said nearest intermediate control point a distance corresponding to said touch-displacement distance in a direction corresponding to said touch-displacement direction.

19. A method as described in claim 12, further comprising subdividing any patch in said edge-aligned mesh wherein a surface curvature associated with said any patch exceeds a first threshold.

20. A method as described in claim 12 further comprising overlaying an intermediate corner-aligned mesh on said displayed document image in response to receiving each of said corner points in said plurality of corner points.