Table of Contents
ISRN Signal Processing
Volume 2013 (2013), Article ID 735857, 7 pages
Research Article

NGFICA Based Digitization of Historic Inscription Images

1Electronics and Communication Engineering Department, Delhi Technological University, Formerly Delhi College of Engineering, Delhi 110042, India
2Electrical Engineering Department, Indian Institute of Technology Delhi, Delhi 110006, India

Received 28 February 2013; Accepted 8 April 2013

Academic Editors: L.-M. Cheng, W.-L. Hwang, and P.-Y. Yin

Copyright © 2013 Indu Sreedevi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper addresses the problems encountered during digitization and preservation of inscriptions such as perspective distortion and minimal distinction between foreground and background. In general inscriptions possess neither standard size and shape nor colour difference between the foreground and background. Hence the existing methods like variance based extraction and Fast ICA based analysis fail to extract text from these inscription images. Natural gradient flexible ICA (NGFICA) is a suitable method for separating signals from a mixture of highly correlated signals, as it minimizes the dependency among the signals by considering the slope of the signal at each point. We propose an NGFICA based enhancement of inscription images. The proposed method improves word and character recognition accuracies of the OCR system by 65.3% (from 10.1% to 75.4%) and 54.3% (from 32.4% to 86.7%), respectively.