Image processing apparatus and image processing method
First Claim
1. An image processing apparatus, comprising:
- an image input unit configured to input a document image;
a reducing unit configured to generate a reduced document image by reducing the document image;
an edge image generating unit configured to generate an edge image by extracting at least one edge of the reduced document image; and
an inclination detecting unit configured to detect an inclination of the document image based on an inclination of a straight line representing an edge of the edge image, wherein said inclination detecting unit detects the straight line representing the edge of the edge image by performing a Hough transformation, and detects the inclination of the document image based on an inclination of the straight line, andwherein said inclination detecting unit is operable, if a plurality of straight lines that have different inclinations are detected, to determine a smallest inclination among the inclinations of the plurality of straight lines to be the inclination of the document image.
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Abstract
The present invention enables inclination detection by detecting an inclination of a document image based on a feature of a document area. In order to achieve this, reduction processing is performed on document image data including the document area so as to generate a reduced document image corresponding to the document area that has been extracted. Thereafter, filter processing is performed on the reduced document image so as to generate an edge image by extracting at least one edge of the document area. Then, a straight line adjoining an edge of the edge image is detected using a Hough transformation so that the inclination of the document image is determined based on an inclination of the straight line. Consequently, inclination detection with high accuracy can be performed based on the feature of the document area.
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Citations
14 Claims
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1. An image processing apparatus, comprising:
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an image input unit configured to input a document image; a reducing unit configured to generate a reduced document image by reducing the document image; an edge image generating unit configured to generate an edge image by extracting at least one edge of the reduced document image; and an inclination detecting unit configured to detect an inclination of the document image based on an inclination of a straight line representing an edge of the edge image, wherein said inclination detecting unit detects the straight line representing the edge of the edge image by performing a Hough transformation, and detects the inclination of the document image based on an inclination of the straight line, and wherein said inclination detecting unit is operable, if a plurality of straight lines that have different inclinations are detected, to determine a smallest inclination among the inclinations of the plurality of straight lines to be the inclination of the document image. - View Dependent Claims (2, 3, 4, 5)
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6. An image processing apparatus, comprising:
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an image input unit configured to input a document image; a reducing unit configured to generate a reduced document image by reducing the document image; an edge image generating unit configured to generate an edge image by extracting at least one edge of the reduced document image; and an inclination detecting unit configured to detect an inclination of the document image based on an inclination of a straight line representing an edge of the edge image, wherein said inclination detecting unit detects the straight line representing the edge of the edge image by performing a Hough transformation and detects the inclination of the document image based on an inclination of the straight line, and wherein said inclination detecting unit is operable, if a plurality of straight lines that have different inclinations are detected, to select two orthogonal lines, and to determine a smaller inclination between the inclinations of the two straight lines to be the inclination of the document image. - View Dependent Claims (7)
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8. An image processing method comprising:
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inputting a document image; generating a reduced document image by reducing the document image; generating an edge image by extracting at least one edge of the reduced document image; and detecting an inclination of the document image based on an inclination of a straight line representing an edge of the edge image, wherein the straight line representing the edge of the edge image is detected by performing a Hough transformation, and the inclination of the document image is detected based on an inclination of the straight line, wherein if a plurality of straight lines that have different inclinations are detected, a smallest inclination among the inclinations of the plurality of straight lines is determined to be the inclination of the document image, and wherein at least one processor executes steps stored in a memory to perform at least one of the inputting, generating, and detecting. - View Dependent Claims (9, 10)
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11. A computer-readable storage medium storing a computer program configured, when run on a computer, to cause said computer to:
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input a document image; generate a reduced document image by reducing the document image; generate an edge image by extracting at least one edge of the reduced document image; and detect an inclination of the document image based on an inclination of a straight line representing an edge of the edge image, wherein the straight line representing the edge of the edge image is detected by performing a Hough transformation, and the inclination of the document image is detected based on an inclination of the straight line, wherein if a plurality of straight lines that have different inclinations are detected, a smallest inclination among the inclinations of the plurality of straight lines is determined to be the inclination of the document image.
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12. An image processing method, comprising:
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inputting a document image; generating a reduced document image by reducing the document image; generating an edge image by extracting at least one edge of the reduced document image; and detecting an inclination of the document image based on an inclination of a straight line representing an edge of the edge image, wherein the straight line representing the edge of the edge image is detected by performing a Hough transformation, and the inclination of the document image is detected based on an inclination of the straight line, wherein if a plurality of straight lines that have different inclinations are detected, two orthogonal lines are selected, and a smaller inclination between the inclinations of the two straight lines is determined to be the inclination of the document image, and wherein at least one processor executes steps stored in a memory to perform at least one of the inputting, generating, and detecting. - View Dependent Claims (13)
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14. A non-transitory computer-readable storage medium storing a computer program configured, when run on a computer, to cause said computer to:
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input a document image; generate a reduced document image by reducing the document image; generate an edge image by extracting at least one edge of the reduced document image; and detecting an inclination of the document image based on an inclination of a straight line representing an edge of the edge image, wherein the straight line representing the edge of the edge image is detected by performing a Hough transformation, and the inclination of the document image is detected based on an inclination of the straight line, and wherein if a plurality of straight lines that have different inclinations are detected, two orthogonal lines are selected, and a smaller inclination between the inclinations of the two straight lines is determined to be the inclination of the document image.
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Specification