Method and apparatus for detection of a skew angle of a document image using a regression coefficient
First Claim
1. A method for detecting a skew angle, comprising the steps of:
- scanning a page of a document and generating a document image;
determining sampling points of the document image using ruled lines of the document image;
calculating a regression coefficient of the sampling points; and
determining the skew angle of the document image using said regression coefficient.
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Accused Products
Abstract
A method and apparatus for detecting the skew angle of a document image. Skew angle determination is performed by the steps of determining a set of sampling points from an input document image and processing X and Y coordinates of the sampling points in order to calculate a regression coefficient of the sampling points. The skew angle of the document is determined using the regression coefficient. To evaluate a calculated skew angle which corresponds to the regression coefficient, a correlation coefficient is calculated and evaluated. As coordinates of sampling points are obtained for a plurality of sets of data corresponding to different ruled lines or lines of characters, a histogram may be used to determine the most probable skew angle.
69 Citations
28 Claims
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1. A method for detecting a skew angle, comprising the steps of:
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scanning a page of a document and generating a document image; determining sampling points of the document image using ruled lines of the document image; calculating a regression coefficient of the sampling points; and determining the skew angle of the document image using said regression coefficient. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for detecting a skew angle, comprising the steps of:
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scanning a page of a document and generating a document image; determining if at least a predetermined number of adjacent pixels forming a ruled line exist; when at least the predetermined number of adjacent pixels forming a line are determined not to exist, performing the steps of; determining sampling points using characters of the document image; calculating a regression coefficient using the determined sampling points; and calculating a skew angle using the regression coefficient. - View Dependent Claims (9, 10, 11)
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12. A system for detecting a skew angle, comprising:
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means for determining sampling points of a document image using ruled lines of the document image; means for calculating a regression coefficient of the sampling points; and means for determine the skew angle of the document image using said regression coefficient. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A method for detecting a skew angle, comprising the steps of:
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scanning a page of a document and generating a document image; determining if a skew angle of the document image can be determined using ruled lines of the document image; determining the skew angle of the document image using the ruled lines of the document image, when the skew angle of the document image can be determined using ruled lines of the document image; and determining the skew angle of the document image using character information, when the skew angle of the document image cannot be determined using the ruled lines of the document image.
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20. A system for detecting a skew angle, comprising:
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a scanning device which scans a page of a document and generates a document image; means for determining if a skew angle of the document image can be determined using ruled lines of the document image; means for determining the skew angle of the document image using the ruled lines of the document image, when the skew angle of the document image can be determined using ruled lines of the document image; and means for determining the skew angle of the document image using character information, when the skew angle of the document image cannot be determined using the ruled lines of the document image.
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21. A method for detecting a skew angle, comprising the steps of:
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scanning a page of a document and generating a document image; determining coordinates for characters of the document image which correspond on a one-to-one basis with the characters of the page; determining sampling points of the document image using the coordinates which have been determined; calculating a regression coefficient of the sampling points; and determining the skew angle of the document image using said regression coefficient. - View Dependent Claims (22, 23, 24)
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25. A system for detecting a skew angle of a page, comprising:
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means for determining coordinates for characters of the page which correspond on a one-to-one basis with the characters of the page; means for determining sampling points of the page using the coordinates which have been determined; means for calculating a regression coefficient of the sampling points; and means for determine the skew angle of the page using said regression coefficient. - View Dependent Claims (26, 27, 28)
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Specification