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Method and system for determining vanishing point candidates for projective correction

  • US 8,897,600 B1
  • Filed: 12/20/2013
  • Issued: 11/25/2014
  • Est. Priority Date: 12/20/2013
  • Status: Active Grant
First Claim
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1. A method for determining vanishing point candidates of a text portion in an image document that is distorted by perspective, comprising the steps of:

  • image binarization, wherein said image is binarized;

    performing connected component analysis, wherein pixel blobs are detected in said at least one text portion of said binarized image and wherein for each of said pixel blobs a position determining pixel is selected on a pixel blob baseline of the pixel blob, said position determining pixel defining the position of the pixel blob in the binarized image;

    estimating a number of text lines in a Cartesian coordinate system, each text line representing an approximation of a horizontal or vertical text direction of said text portion, on the basis of the position determining pixels;

    transforming each of said text lines to a data point in a homogenous coordinate system;

    assigning a confidence level to each of the data points;

    grouping a number of data points having a confidence level above a predetermined threshold into a priority sample array;

    clustering the data points in the priority sample array into a number of sample groups, wherein each sample group comprises at least two data points;

    assigning a group confidence value to each sample group on the basis of at least the confidence level assigned to each data point in the sample group;

    applying a RANSAC algorithm to determine among said data points a set of inliers with respect to a first fitted line, wherein said RANSAC algorithm is initiated with the sample group having the highest group confidence value in the priority sample array;

    estimating at least one vanishing point candidate from the text lines corresponding to said set of inliers.

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