System and method for scanned document correction
First Claim
1. A method for the correction of a warped page image, the method comprising:
- accepting a camera image of a page;
creating a filtered edge map and identifying text-likely regions;
projecting the filtered edge map and text-likely regions into a polar coordinate system to determine page lines and warped image page curves;
subsequent to projecting the filtered edge map and text-likely regions into the polar coordinate system, histogramming the filtered and projected edge map into theta bins, computing minimum and maximum theta angles for text-likely regions, localizing a first page line as a closest significant edge bin less than minimum text-likely region theta angle and a second page line as a closest significant edge bin greater than maximum text-likely region theta angle;
creating an adaptive two-dimensional (2D) ruled mesh piecewise planar approximation of a warped page surface;
using the created adaptive two-dimensional (2D) ruled mesh piecewise planar approximation of a warped page surface for estimating a camera focal length;
creating a three-dimensional (3D) model using the adaptive 2D ruled mesh and camera focal length estimate; and
,using the 3D model, creating a 2D target mesh rectifying the image of the page;
wherein rectifying the image of the page includes using a perspective dewarp to interpolate image values from the adaptive 2D ruled mesh into the image defined by the 2D target rectilinear mesh.
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Accused Products
Abstract
A system and method are provided for the correction of a warped page image. The method first accepts a camera image of a page, creates a filtered edge map, and identifies text-likely regions. The filtered edge map and text-likely regions are projected into a polar coordinate system to determine page lines and warped image page curves. An adaptive two-dimensional (2D) ruled mesh piecewise planar approximation of a warped page surface is created. A three-dimensional (3D) model is created using the adaptive 2D ruled mesh and the estimate of the camera focal length estimate. Using the 3D model, a 2D target mesh is created for rectifying the image of the page. In one aspect, the adaptive 2D ruled mesh is projected onto a 3D warped page surface using the estimated camera focal length and an estimated surface normal of each planar strip from the adaptive 2D ruled mesh.
34 Citations
24 Claims
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1. A method for the correction of a warped page image, the method comprising:
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accepting a camera image of a page; creating a filtered edge map and identifying text-likely regions; projecting the filtered edge map and text-likely regions into a polar coordinate system to determine page lines and warped image page curves; subsequent to projecting the filtered edge map and text-likely regions into the polar coordinate system, histogramming the filtered and projected edge map into theta bins, computing minimum and maximum theta angles for text-likely regions, localizing a first page line as a closest significant edge bin less than minimum text-likely region theta angle and a second page line as a closest significant edge bin greater than maximum text-likely region theta angle; creating an adaptive two-dimensional (2D) ruled mesh piecewise planar approximation of a warped page surface; using the created adaptive two-dimensional (2D) ruled mesh piecewise planar approximation of a warped page surface for estimating a camera focal length; creating a three-dimensional (3D) model using the adaptive 2D ruled mesh and camera focal length estimate; and
,using the 3D model, creating a 2D target mesh rectifying the image of the page;
wherein rectifying the image of the page includes using a perspective dewarp to interpolate image values from the adaptive 2D ruled mesh into the image defined by the 2D target rectilinear mesh. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for the correction of a warped page image, the system comprising:
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a non-transitory memory; a processor; an interface to accept a camera image of a page, and to supply a rectified image of the page; an image correction application stored in the memory and enabled as a sequence of processor executable steps for; creating a filtered edge map and identifying text-likely regions; projecting the filtered edge map and text-likely regions into a polar coordinate system to determine page lines and warped image page curves; subsequent to projecting the filtered edge map and text-likely regions into the polar coordinate system, histograms the filtered and projected edge map into theta bins, computes minimum and maximum theta angles for text-likely regions, and localizes a first page line as a closest significant edge bin less than minimum text-likely region theta angle and a second page line as a closest significant edge bin greater than maximum text-likely region theta angle; creating an adaptive two-dimensional (2D) ruled mesh piecewise planar approximation of a warped page surface; using the created adaptive two-dimensional (2D) ruled mesh piecewise planar approximation of a warped page surface for estimating a camera focal length; creating a three-dimensional (3D) model using the adaptive 2D ruled mesh and camera focal length estimate; and
,using the 3D model, creating a 2D target mesh rectifying the image of the page;
wherein the image correction application rectifies the image of the page using a perspective dewarp to interpolate image values from the adaptive 2D ruled mesh into the image defined by the 2D target rectilinear mesh. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification