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Mathematical Problems in Engineering
Volume 2014 (2014), Article ID 848615, 10 pages
Research Article

Local Contrast Enhancement Utilizing Bidirectional Switching Equalization of Separated and Clipped Subhistograms

1School of Electrical & Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia
2Japan-Malaysia Technical Institute (JMTI), Plot 59, Lorong Perindustrian Bukit Minyak 15, Taman Perindustrian Bukit Minyak, 14100 Simpang Ampat, Penang, Malaysia

Received 11 October 2013; Revised 26 December 2013; Accepted 5 January 2014; Published 12 February 2014

Academic Editor: Suh-Yuh Yang

Copyright © 2014 Haidi Ibrahim and Seng Chun Hoo. 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.


Digital image contrast enhancement methods that are based on histogram equalization technique are still useful for the use in consumer electronic products due to their simple implementation. However, almost all the suggested enhancement methods are using global processing technique, which does not emphasize local contents. Therefore, this paper proposes a new local image contrast enhancement method, based on histogram equalization technique, which not only enhances the contrast, but also increases the sharpness of the image. Besides, this method is also able to preserve the mean brightness of the image. In order to limit the noise amplification, this newly proposed method utilizes local mean-separation, and clipped histogram bins methodologies. Based on nine test color images and the benchmark with other three histogram equalization based methods, the proposed technique shows the best overall performance.