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International Journal of

Recent Trends in Engineering

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International Journal of Recent Trends in Engineering (IJRTE)

ISSN 1797-9617

Volume 1, Number 4, May 2009

Issue on Electrical & Electronics

Page(s): 82-84

Bi-level Histogram Equalization Based Histogram Shaping Technique for Contrast Enhancement in Spectral Domain with Maximum Enhancement by Entropy Measure

Abhinav.V, Rishabh Gupta, Ravi Tej Akula, M.R.Vimala Devi

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Abstract

The main objective of image enhancement is to improve some characteristic of an image to make it visually a better one. Enhancement techniques can be divided into two categories namely: spatial domain methods and transform domain methods. Spatial domain technique enhances an image by directly dealing with the intensity value in an image. Transform domain enhancement techniques involve transforming the image intensity data into a specific domain by using methods such as DFT, DCT, etc. and the image is enhanced by altering the frequency content of the image. Each of these methods has strong and weak points. Hence, the combination of the above two methods are used to enhance the image in this paper. This paper proposes three methods of image enhancement by using logarithmic transform coefficient histogram mapping, shifting and shaping techniques with brightness preserving bi-level histogram equalization. The proposed methods performs well compared to logarithmic transform histogram mapping, shifting and shaping techniques using the traditional histogram equalization and this has been proved with Enhancement by entropy as a performance measure.

Index Terms

image enhancement; transform coefficient histogram; histogram mapping

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