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Journal of Engineering
Volume 2013, Article ID 465469, 11 pages
Research Article

Printed Persian Subword Recognition Using Wavelet Packet Descriptors

Faculty of Electrical Engineering, Sahand University of Technology, Tabriz, Iran

Received 30 May 2013; Accepted 7 August 2013

Academic Editor: Yangmin Li

Copyright © 2013 Samira Nasrollahi and Afshin Ebrahimi. 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.


In this paper, we present a new approach to offline OCR (optical character recognition) for printed Persian subwords using wavelet packet transform. The proposed algorithm is used to extract font invariant and size invariant features from 87804 subwords of 4 fonts and 3 sizes. The feature vectors are compressed using PCA. The obtained feature vectors yield a pictorial dictionary for which an entry is the mean of each group that consists of the same subword with 4 fonts in 3 sizes. The sets of these features are congregated by combining them with the dot features for the recognition of printed Persian subwords. To evaluate the feature extraction results, this algorithm was tested on a set of 2000 subwords in printed Persian text documents. An encouraging recognition rate of 97.9% is got at subword level recognition.