Correcting device and method for perspective transformed document images
First Claim
1. A correcting device for a perspective transformed document image, said correcting device comprising:
- a horizontal vanishing point determining unit, for detecting a horizontal vanishing point of the perspective transformed document image;
a vertical vanishing point determining unit, for detecting a vertical vanishing point of the perspective transformed document image; and
a perspective transformation correcting and converting unit, for correcting the perspective transformed document image;
wherein the horizontal vanishing point determining unit comprises a direct horizontal line segment detecting unit, an indirect horizontal line segment detecting unit and a horizontal vanishing point detecting unit, and wherein the horizontal vanishing point detecting unit detects a horizontal vanishing point in accordance with direct horizontal line segments detected by the direct horizontal line segment detecting unit and indirect horizontal line segments detected by the indirect horizontal line segment detecting unit; and
wherein the horizontal vanishing point detecting unit comprises;
a horizontal line segment intersection point clustering unit, for clustering point collections formed by intersection points of two horizontal line segments in a collection formed by direct horizontal line segments and indirect horizontal line segments to obtain a plurality of clusters;
a candidate horizontal vanishing point selecting unit, for selecting each cluster as a candidate horizontal vanishing point and obtaining a weight coefficient of each candidate horizontal vanishing point;
a horizontal direction perspective projection analyzing unit, for performing perspective projection analysis in a horizontal direction on the document image with regard to the candidate horizontal vanishing points and obtaining another weight coefficient of each candidate horizontal vanishing point; and
a horizontal vanishing point synthesis analyzing unit, for selecting a final horizontal vanishing point in accordance with the weight coefficient and the another weight coefficient of each of the candidate horizontal vanishing points.
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Abstract
This invention provides a correcting device and a correcting method for perspective transformation of document images. The correcting device comprises a horizontal vanishing point determining unit, for detecting a horizontal vanishing point of the perspective transformed document image; a vertical vanishing point determining unit, for detecting a vertical vanishing point of the perspective transformed document image; and a perspective transformation correcting and converting unit, for correcting the perspective transformed document image; wherein the horizontal vanishing point determining unit comprises a direct horizontal line segment detecting unit, an indirect horizontal line segment detecting unit and a horizontal vanishing point detecting unit, and wherein the horizontal vanishing point detecting unit detects a horizontal vanishing point in accordance with a direct horizontal line segment detected by the direct horizontal line segment detecting unit and an indirect horizontal line segment detected by the indirect horizontal line segment detecting unit.
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Citations
18 Claims
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1. A correcting device for a perspective transformed document image, said correcting device comprising:
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a horizontal vanishing point determining unit, for detecting a horizontal vanishing point of the perspective transformed document image; a vertical vanishing point determining unit, for detecting a vertical vanishing point of the perspective transformed document image; and a perspective transformation correcting and converting unit, for correcting the perspective transformed document image; wherein the horizontal vanishing point determining unit comprises a direct horizontal line segment detecting unit, an indirect horizontal line segment detecting unit and a horizontal vanishing point detecting unit, and wherein the horizontal vanishing point detecting unit detects a horizontal vanishing point in accordance with direct horizontal line segments detected by the direct horizontal line segment detecting unit and indirect horizontal line segments detected by the indirect horizontal line segment detecting unit; and wherein the horizontal vanishing point detecting unit comprises; a horizontal line segment intersection point clustering unit, for clustering point collections formed by intersection points of two horizontal line segments in a collection formed by direct horizontal line segments and indirect horizontal line segments to obtain a plurality of clusters; a candidate horizontal vanishing point selecting unit, for selecting each cluster as a candidate horizontal vanishing point and obtaining a weight coefficient of each candidate horizontal vanishing point; a horizontal direction perspective projection analyzing unit, for performing perspective projection analysis in a horizontal direction on the document image with regard to the candidate horizontal vanishing points and obtaining another weight coefficient of each candidate horizontal vanishing point; and a horizontal vanishing point synthesis analyzing unit, for selecting a final horizontal vanishing point in accordance with the weight coefficient and the another weight coefficient of each of the candidate horizontal vanishing points. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A correcting device for a perspective transformed document image, said correcting device comprising:
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a horizontal vanishing point determining unit, for detecting a horizontal vanishing point of the perspective transformed document image; a vertical vanishing point determining unit, for detecting a vertical vanishing point of the perspective transformed document image; and a perspective transformation correcting and converting unit, for correcting the perspective transformed document image; wherein the vertical vanishing point determining unit comprises a direct vertical line segment detecting unit, an indirect vertical line segment detecting unit and a vertical vanishing point detecting unit, and wherein the vertical vanishing point detecting unit detects a vertical vanishing point in accordance with direct vertical line segments detected by the direct vertical line segment detecting unit and indirect vertical line segments detected by the indirect vertical line segment detecting unit; and wherein the vertical vanishing point detecting unit comprises; a vertical line segment intersection point clustering unit, for clustering point collections formed by intersection points of every two vertical line segments in a collection formed by the direct vertical line segment and the indirect vertical line segment to obtain a plurality of clusters; a vertical vanishing point selecting unit, for selecting the central point of each cluster as a candidate vertical vanishing point and obtaining a weight coefficient of each candidate vertical vanishing point; a vertical direction perspective projection analyzing unit, for performing perspective projection analysis in a vertical direction on the document image with regard to each candidate vertical vanishing point and obtaining another weight coefficient of each candidate vertical vanishing point; and a vertical vanishing point synthesis analyzing unit, for analyzing the weight coefficient obtained by the vertical vanishing point selecting unit and the another weight coefficient obtained by the vertical direction perspective projection analyzing unit with regard to each candidate vertical vanishing point to obtain a final vertical vanishing point. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A correcting method for a perspective transformed document image, carried out by a correcting device for a perspective transformed document image, said correcting method comprising:
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a horizontal vanishing point determining step, for detecting a horizontal vanishing point of the perspective transformed document image; a vertical vanishing point determining step, for detecting a vertical vanishing point of the perspective transformed document image; and a perspective transformation correcting and converting step, for correcting the perspective transformed document image; wherein the horizontal vanishing point determining step comprises a direct horizontal line segment detecting step, an indirect horizontal line segment detecting step and a horizontal vanishing point detecting step, and wherein the horizontal vanishing point detecting step detects a horizontal vanishing point in accordance with a direct horizontal line segment detected by the direct horizontal line segment detecting step and an indirect horizontal line segment detected by the indirect horizontal line segment detecting step, and wherein the horizontal vanishing point detecting step comprises; clustering point collections formed by intersection points of every two horizontal line segments in a collection formed by all direct horizontal line segments and indirect horizontal line segments to obtain a plurality of clusters; selecting the central point of each cluster as a candidate horizontal vanishing point and obtaining a weight coefficient of each candidate horizontal vanishing point; performing perspective projection analysis in a horizontal direction on the document image with regard to the candidate horizontal vanishing point and obtaining another weight coefficient of each candidate horizontal vanishing point; and selecting a final horizontal vanishing point in accordance with the weight coefficient and the another weight coefficient of each of the candidate horizontal vanishing point.
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18. A correcting method for a perspective transformed document image, carried out by a correcting device for a perspective transformed document image, said correcting method comprising:
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a horizontal vanishing point determining step, for detecting a horizontal vanishing point of the perspective transformed document image; a vertical vanishing point determining step, for detecting a vertical vanishing point of the perspective transformed document image; and a perspective transformation correcting and converting step, for correcting the perspective transformed document image; wherein the vertical vanishing point determining step comprises a direct vertical line segment detecting step, an indirect vertical line segment detecting step and a vertical vanishing point detecting step, and wherein the vertical vanishing point detecting step detects a vertical vanishing point in accordance with a direct vertical line segment detected by the direct vertical line segment detecting step and an indirect vertical line segment detected by the indirect vertical line segment detecting step, and wherein the vertical vanishing point detecting step comprises; clustering point collections formed by intersection points of every two vertical line segments in a collection formed by the direct vertical line segment and the indirect vertical line segment to obtain a plurality of clusters; selecting the central point of each cluster as a candidate vertical vanishing point and obtaining a weight coefficient of each candidate vertical vanishing point; performing perspective projection analysis in a vertical direction on the document image with regard to each candidate vertical vanishing point and obtaining another weight coefficient of each candidate vertical vanishing point; and analyzing the weight coefficient obtained by the selecting and the another weight coefficient obtained by the performing and obtaining with regard to each candidate vertical vanishing point to obtain a final vertical vanishing point.
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Specification