Document image de-warping based on detection of distorted text lines

Abstract

Image warping caused by scanning, photocopying or photographing a document is a common problem in the field of document processing and understanding. Distortion within the text documents impairs OCRability and thus strongly decreases the usability of the results. This is one of the major obstacles for automating the process of digitizing printed documents. In this paper we present a novel algorithm which is able to correct document image warping based on the detection of distorted text lines. The proposed solution is used in a recent project of digitizing old, poor quality manuscripts. The algorithm is compared to other published approaches. Experiments with various document samples and the resulting improvements of the text recognition rate achieved by a commercial OCR engine are also presented. © Springer-Verlag Berlin Hiedelberg 2005.