CAMERA-BASED DOCUMENT IMAGING

摘要

A process and system to transform a digital photograph of a text document into a scan-quality image is disclosed. By extracting the document text from the image, and analyzing visual clues from the text, a grid is constructed over the image representing the distortions in the image. Transforming the image to straighten this grid removes distortions introduced by the camera image-capture process. Variations in lighting, the extraction of text line information, and the modeling of curved lines in the image may be corrected.

主权项

1. A method for processing a photographed image containing text lines comprising text characters having vertical strokes comprising:
(a) binarization using pixel normalized thresholding to identify pixels in the image that make up the text; (b) detecting typographical features indicative of the orientation of text; (c) fitting one or more curves to a text line; (d) building a grid of quadrilaterals using vectors that are parallel to the direction of the text lines and vectors parallel to the direction of the vertical stroke lines; (e) dewarping the document by stretching the image so that vectors parallel to the text lines and vectors parallel to the direction of the vertical stroke lines become orthogonal; and (f) processing the dewarped document with an optical character recognition software.