Patent Document ID: 8811751
Application ID: 14136695

Base Claim:
1. A method for projective correction of an image containing at least one text portion that is distorted by perspective, the method comprising the steps of: image binarization, wherein said image is binarized; 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; horizontal vanishing point determination, comprising the steps of: estimating text baselines by means of said position determining pixels of said pixel blobs, identifying horizontal vanishing point candidates from said estimated text baselines, and determining a horizontal vanishing point of said at least one text portion by means of said horizontal vanishing point candidates; vertical vanishing point determination, wherein a vertical vanishing point is determined for said at least one text portion on the basis of vertical features thereof; and projective correction, wherein said perspective in said image is corrected on the basis of said horizontal and vertical vanishing points; wherein said horizontal vanishing point determination comprises a first elimination step on the level of said position determining pixels, a second elimination step on the level of text baselines and a third elimination step on the level of horizontal vanishing point candidates.

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Claim 12:
12. Method according to claim 1 , wherein a first and a second horizontal vanishing point candidate are estimated from said text baselines after said second elimination step and wherein for said estimation of said first and second horizontal vanishing point candidates different approximation methods are used, chosen from the group consisting of: a least squares method, a weighted least squares method and an adaptive least squares method.