Automatic Correction of Digital Image Distortion

• US 20100014782A1
• Filed: 07/15/2008
• Published: 01/21/2010
• Est. Priority Date: 07/15/2008
• Status: Active Grant

• Current Assignee: Kofax Incorporated
• Original Assignee: Nuance Communications, Inc. (Microsoft Corporation)
• Inventors: Tamasi, Gyorgy, Fero, Laszlo, Solymosi, Pal
• Granted Patent: US 8,285,077 B2
• Time in Patent Office: Days
• US Class Current: 382/290
• CPC Class Codes: G06V 10/243 by compensating for image skew or non-uniform image deformations
• CPC Class Codes: H04N 1/387 Composing, repositioning or otherwise geometrically modifying originals

Abstract

A method of de-skewing a digital image is described. An input camera image is initially received, and text within the input camera image is identified. A text direction of the identified text is determined to determine text lines within the camera image. A three-dimensional de-skewing transformation is determined of the text lines to make the text lines horizontal. Then the de-skewing transformation is applied to the input camera image to form a de-skewed output image. An unwarping transformation may also be applied to the input camera image for straightening text lines that are curved.

Claims

1. A method of de-skewing a digital image comprising:

receiving an input camera image;

identifying text within the input camera image;

determining a text direction of the identified text to determine text lines within the camera image;

creating a three-dimensional de-skewing transformation of the text lines to make the text lines horizontal; and

applying the de-skewing transformation to the input camera image to form a de-skewed output image.

2. A method according to claim 1, wherein identifying text includes determining black connected components within the input camera image.

3. A method according to claim 2, wherein identifying text includes identifying and ignoring non-text components in the input camera image.

4. A method according to claim 1, wherein determining a text direction includes determining a horizontal text direction.

5. A method according to claim 1, wherein determining a text direction includes determining a vertical text direction.

6. A method according to claim 1, further comprising:

applying an unwarping transformation to the input camera image for straightening text lines that are curved.

7. A computer program product in a computer readable storage medium for de-skewing a digital image, the product comprising:

program code for receiving an input camera image;

program code for identifying text within the input camera image;

program code for determining a text direction of the identified text to determine text lines within the camera image;

program code for creating a three-dimensional de-skewing transformation of the text lines to make the text lines horizontal; and

program code for applying the de-skewing transformation to the input camera image to form a de-skewed output image.

8. A product according to claim 7, wherein the program code for identifying text includes program code for determining black connected components within the input camera image.

9. A product according to claim 8, wherein the program code for identifying text includes program code for identifying and ignoring non-text components in the input camera image.

10. A product according to claim 7, wherein the program code for determining a text direction includes program code for determining a horizontal text direction.

11. A product according to claim 7, wherein the program code for determining a text direction includes program code for determining a vertical text direction.

12. A product according to claim 7, further comprising:

program code for applying an unwarping transformation to the input camera image for straightening text lines that are curved.