NDLI: A Study on the Validation of Histogram Equalization as a Contrast Enhancement Technique

Content Provider	IEEE Xplore Digital Library
Author	Ahmed, M.M. Zain, J.M.
Copyright Year	2012
Abstract	Our study uncovers that histogram equalization (HE) - in a striking contrast to it's claim - is not related to enhancement of contrast. To understand this view, we start with real world images which have varying degree of image quality that almost invariably require processing to improve image contrast. For this purpose, histogram equalization including its variants is a frequently relied upon technique. HE processes image by calculating pixel density of its constituent gray levels. This mathematical model, described by HE, is neither linked to contrast nor is contrast directly included in HE equations. Therefore, the study aims to find out the factual nature of transformation functions used by HE. To understand these mathematical calculations thoroughly, the paper dismantles HE into it's building blocks. These blocks are, then, critically analyzed to understand the true relationship between HE fundamentals and contrast. This analysis' determines that HE manipulates density - not contrast - which, in turn, achieves density changes but no contrast enhancement. Hence the study concludes that HE is not a valid contrast enhancement technique.
Starting Page	253
Ending Page	256
File Size	324698
Page Count	4
File Format	PDF
ISBN	9781467358323
e-ISBN	9780769549590
DOI	10.1109/ACSAT.2012.82
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2012-11-26
Publisher Place	Malaysia
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Probability density Histogram Equalization Contrast HE Cumulative density function
Content Type	Text
Resource Type	Article

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