Skew Correction for Scanned Japanese/English Document Images
First Claim
1. A method for applying skew correction to an input image including providing a processing device to implement steps comprising:
- identifying an alignment of consecutive characters on said input image defining a character line;
estimating a line orientation angle of said character line;
defining a document skew angle from said line orientation angle;
rotating said input image by an amount determined to counteract said document skew angle.
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Accused Products
Abstract
Bit data is encoded into characters in an input image by providing different darkness levels for pixels in either half of a text character. In order to detect document skew angle error prior to attempting to extract an encoded message, the orientation angle of text line(s) in the input image is determined, and a document skew angle is estimated from the line orientation angle(s). A Hough transform may be used to estimate line orientation angle. To determine if an input image of a document is orientated horizontally or vertically, the input image may be scanned for text characters along a first reference angle, and along a second angle 90° to the first angle. The scan that provides the higher number of potential text character is selected as the correct orientation for the input image.
40 Citations
24 Claims
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1. A method for applying skew correction to an input image including providing a processing device to implement steps comprising:
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identifying an alignment of consecutive characters on said input image defining a character line; estimating a line orientation angle of said character line; defining a document skew angle from said line orientation angle; rotating said input image by an amount determined to counteract said document skew angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An image processing device for applying skew correction to an input image, comprising:
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an input for receiving said input image; a site detection unit for identifying bounding boxes around characters in said input image; a centroid estimation unit for identifying a centroid of each bounding box; a text line orientation unit for determining an orientation angle for at least one line of characters within said input image; a document orientation unit for determining a document skew angle for said input image based on the angle orientation results of said text line orientation unit; an orientation correction unit for rotating said input image by an amount determined to counteract said document skew angle.
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- 21. The image processing device of claim 21, wherein said at least one line of characters is the longest line of characters within said input image, and said document skew angle is set equal to the orientation angle of the longest line of characters in said input image.
Specification