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US 2017/0366705 A1Published application
Image-processing apparatus, method, and computer program product for correcting skew in scanned images
AssigneePfu Limited
InventorTomoaki WADA
Life of this patent
Estimating the term…
Abstract
According to the present disclosure, edges of a document image contained in a read image read by an image-reading apparatus including a paper path are detected, a candidate edge-skew occurrence position is detected, a candidate content-skew occurrence position is detected, an accumulated-skew occurrence position is detected based on the candidate edge-skew occurrence position and the candidate content-skew occurrence position, skew of a document rear-part image rearward from the accumulated-skew occurrence position in the conveyance direction is corrected, and image data corrected for accumulated skew is acquired.
Claims18
An image-processing apparatus comprising:
- an image acquiring unit configured to acquire read image data of a read image read by an image-reading apparatus including a paper path;
- an edge detecting unit configured to detect edges of a document image contained in the read image and acquires approximate straight lines by extending the longest straight-line parts of the respective edges;
- an edge-skew detecting unit configured to detect, as a candidate edge-skew occurrence position, on one of the approximate straight lines that is in a document conveyance direction, a position at which the one approximate straight line and an edge containing the longest straight-line part of the one approximate straight line start to separate from each other;
- a content detecting unit configured to detect direction-identifying contents defined as contents usable for specifying directions within the document image;
- a content-skew detecting unit configured to detect, as a candidate content-skew occurrence position, on the one of the approximate straight lines in the conveyance direction, a position at which a rear angle is larger than a front angle and at which the front angle first becomes equal to or more than a certain angle, the front angle being an angle between the one approximate straight line and each of the direction-identifying contents, the rear angle being an angle between the one approximate straight line and one of the direction-identifying contents that is located rearward from the each of the direction-identifying contents in the conveyance direction;
- an accumulated-skew detecting unit configured to detect an accumulated-skew occurrence position, based on the candidate edge-skew occurrence position and the candidate content-skew occurrence position;
- and
- an accumulated-skew correcting unit configured to acquire accumulated-skew-corrected image data by correcting skew in a document rear-part image located rearward from the accumulated-skew occurrence position in the conveyance direction.
5 more elements
An image-processing method comprising:
- an image acquiring step of acquiring read image data of a read image read by an image-reading apparatus including a paper path;
- an edge detecting step of detecting edges of a document image contained in the read image and acquiring approximate straight lines by extending the longest straight-line parts of the respective edges;
- an edge-skew detecting step of detecting, as a candidate edge-skew occurrence position, on one of the approximate straight lines that is in a document conveyance direction, a position at which the one approximate straight line and an edge containing the longest straight-line part of the one approximate straight line start to separate from each other;
- a content detecting step of detecting direction-identifying contents defined as contents usable for specifying directions within the document image;
- a content-skew detecting step of detecting, as a candidate content-skew occurrence position, on the one of the approximate straight lines in the conveyance direction, a position at which a rear angle is larger than a front angle and at which the front angle first becomes equal to or more than a certain angle, the front angle being an angle between the one approximate straight line and each of the direction-identifying contents, the rear angle being an angle between the one approximate straight line and one of the direction-identifying contents that is located rearward from the each of the direction-identifying contents in the conveyance direction;
- an accumulated-skew detecting step of detecting an accumulated-skew occurrence position, based on the candidate edge-skew occurrence position and the candidate content-skew occurrence position;
- and
- an accumulated-skew correcting step of acquiring accumulated-skew-corrected image data by correcting skew in a document rear-part image located rearward from the accumulated-skew occurrence position in the conveyance direction.
5 more elements
A computer program product having a non-transitory tangible computer readable medium including programmed instructions for causing, when executed by a computer,
- the computer to perform an image-processing method comprising:
- an image acquiring step of acquiring read image data of a read image read by an image-reading apparatus including a paper path;
- an edge detecting step of detecting edges of a document image contained in the read image and acquiring approximate straight lines by extending the longest straight-line parts of the respective edges;
- an edge-skew detecting step of detecting, as a candidate edge-skew occurrence position, on one of the approximate straight lines that is in a document conveyance direction, a position at which the one approximate straight line and an edge containing the longest straight-line part of the one approximate straight line start to separate from each other;
- a content detecting step of detecting direction-identifying contents defined as contents usable for specifying directions within the document image;
- a content-skew detecting step of detecting, as a candidate content-skew occurrence position, on the one of the approximate straight lines in the conveyance direction, a position at which a rear angle is larger than a front angle and at which the front angle first becomes equal to or more than a certain angle, the front angle being an angle between the one approximate straight line and each of the direction-identifying contents, the rear angle being an angle between the one approximate straight line and one of the direction-identifying contents that is located rearward from the each of the direction-identifying contents in the conveyance direction;
- an accumulated-skew detecting step of detecting an accumulated-skew occurrence position, based on the candidate edge-skew occurrence position and the candidate content-skew occurrence position;
- and
- an accumulated-skew correcting step of acquiring accumulated-skew-corrected image data by correcting skew in a document rear-part image located rearward from the accumulated-skew occurrence position in the conveyance direction.
6 more elements
Dependencies are inferred from the claim text.