Model-based dewarping method and apparatus

• US 7,697,776 B2
• Filed: 02/12/2008
• Issued: 04/13/2010
• Est. Priority Date: 03/02/2006
• Status: Active Grant

• Current Assignee: Compulink Management Center Incorporated
• Original Assignee: Compulink Management Center Incorporated
• Inventors: Li, Wenxin, Wu, Minghui, Li, Rongfeng, Chan, Karl, Rapelje, Kurt A., Heaney, Edward P. Jr.
• Primary Examiner(s): BHATNAGAR, ANAND P
• Application Number:
  US12/030,167
• Publication Number:
  US 20080144971A1
• Time in Patent Office: 791 Days
• Field of Search: 382/100, 382/181, 382/190, 382/192, 382/193, 382/195, 382/199, 382/206, 382/216, 382/254, 382/255, 382/263, 382/266, 382/268, 382/269, 382/275, 382/286, 382/289, 358/3.26, 358/3.27, 358/448, 358/449, 358/451, 713/503, 714/700
• US Class Current: 382/254
• CPC Class Codes: G06T 2207/30176 Document
• CPC Class Codes: G06T 3/06 Topological mapping of higher dimensional structures onto lower dimensional surfaces
• CPC Class Codes: G06T 5/00 Image enhancement or restoration
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/1444 Selective acquisition, locating or processing of specific regions, e.g. highlighted text, fiducial marks or predetermined fields
• CPC Class Codes: G06V 30/1478 of characters or characters lines
• CPC Class Codes: G06V 30/414 Extracting the geometrical structure, e.g. layout tree; Block segmentation, e.g. bounding boxes for graphics or text
• CPC Class Codes: H04N 1/387 Composing, repositioning or otherwise geometrically modifying originals

Abstract

An apparatus and method for processing a captured image and, more particularly, for processing a captured image comprising a document. In one embodiment, an apparatus comprising a camera to capture documents is described. In another embodiment, a method for processing a captured image that includes a document comprises the steps of distinguishing an imaged document from its background, adjusting the captured image to reduce distortions created from use of a camera and properly orienting the document is described.

Claims

1. A computerized method for processing a captured image that comprises an imaged document, said computerized method comprising:

isolating the imaged document from background of the captured image based on one or more lines corresponding to edges of the imaged document;

setting a curved coordinate net for the imaged document;

stretching the curved coordinate net to a rectangular coordinate net;

calculating the deviation between the curved coordinate net and the rectangular coordinate net; and

resampling pixels of the imaged document based on the calculated deviations.

2. The computerized method recited in claim 1, wherein the curved coordinate net defines coordinates for every pixel forming the imaged document.

3. The computerized method recited in claim 2, further comprising the steps of:

mapping coordinates of pixels of the imaged document to coordinates corresponding to the non-distorted perspective of the imaged document based on the calculated deviation.

4. The computerized method recited in claim 3, further comprising the steps of:

rotating the non-distorted imaged document according to a determination of format of the non-distorted imaged document.

5. A computer system for processing a captured image, the captured image comprising an imaged document, the computer system comprising:

means for isolating the imaged document from background of the captured image based on one or more lines corresponding to edges of the imaged document;

means for setting a curved coordinate net for the imaged document;

means for calculating the deviation between the curved coordinate net and a rectangular coordinate net; and

means for adjusting the rectangle coordinate net to a well-proportional rectangular coordinate net.

6. The computer system recited in claim 5, further comprising:

means for mapping coordinates of pixels of the imaged document to coordinates corresponding to a non-distorted perspective of the imaged document based on the computed deviation.

7. The computer system recited in claim 6, further comprising:

means for rotating the non-distorted imaged document according to a determination of format of the non-distorted imaged document.

8. A computer system comprising one or more processors for processing a captured image comprising an imaged document, the computer system carrying one or more sequences of one or more instructions which, when executed by the one or more processors, cause the one or more processors to perform the computer-implemented steps of:

isolating the imaged document from background of the captured image based on one or more lines corresponding to edges of the imaged document;

setting a curved coordinate net for the imaged document;

calculating the deviation between the curved coordinate net and a rectangular coordinate net; and

adjusting the rectangular coordinate net to a well-proportional rectangular coordinate net.

9. The computer system recited in claim 8, wherein the one or more sequences of one or more instructions further cause the one or more processors to perform the computer-implemented steps of:

mapping coordinates of pixels of the imaged document to coordinates corresponding to a non-distorted perspective of the imaged document based on the computed deviation.

10. The computer system recited in claim 9, wherein the one or more sequences of one or more instructions further cause the one or more processors to perform the computer-implemented steps of:

rotating the non-distorted imaged document according to a determination of format of the non-distorted imaged document.

11. A computer readable storage medium for processing a captured image comprising an imaged document, the computer readable medium carrying one or more sequences of one or more instructions which, when executed by one or more processors, cause the one or more processors to perform the computer-implemented steps of:

isolating the imaged document from background of the captured image based on one or more lines corresponding to edges of the imaged document;

setting a curved coordinate net for the imaged document;

calculating the deviation between the curved coordinate net and a rectangular coordinate net; and

adjusting the rectangular coordinate net to a well-proportional rectangular coordinate net.

12. The computer readable storage medium recited in claim 11, wherein the one or more sequences of one or more instructions further cause the one or more processors to perform the computer-implemented steps of:

mapping coordinates of pixels of the imaged document to coordinates corresponding to a non-distorted perspective of the imaged document based on the computed deviation.

13. The computer readable storage medium recited in claim 12, wherein the one or more sequences of one or more instructions further cause the one or more processors to perform the computer-implemented steps of:

rotating the non-distorted imaged document according to a determination of format of the non-distorted imaged document.