International Journal of Image, Graphics and Signal Processing(IJIGSP)

ISSN: 2074-9074 (Print), ISSN: 2074-9082 (Online)

Published By: MECS Press

IJIGSP Vol.12, No.6, Dec. 2020

Variance Value Limited Clipping of Pentile based Sub-histogram Equalization for Contrast Enhancement of Image

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Kuldip Acharya, Dibyendu Ghoshal

Index Terms

Contrast enhancement, Histogram clipping, Histogram Equalization, Image enhancement, Variance.


Digital image enhancement is a technique to process a digital image to improve the overall visual quality of image. In this paper, Variance concept based clipping threshold value is computed from input image pixel intensity to limit the rate of over enhancement. The histogram of the original image is sub-divided into five adjacent sections and the boundary values between adjacent sections are put from the penile value of intensity range. Besides, over enhancement of the image is avoided by clipping certain number of pixels having more intensity than the clipping limit and these pixels are rearranged below the clipping limit. The present method offers two advantages viz., clipping of the certain pixels based on the property of the data set itself. The another one is to histogram processing by parts and this has given better visual quality, low computation time with improved metrics related to image enhancement. Histogram of each specific sub-image is equalized independently and then combined to produce the final contrast enhanced image. The final output image is further processed through imreducehaze filter for more improve result. Quantitative evaluation of proposed algorithm is performed by CPCQI and QILV image quality metrics and the simulation results have shown that the proposed variance based histogram equalization algorithm produces better quality of image in terms of contrasts, brightness and color in comparison to the other existing histogram equalization algorithms.

Cite This Paper

Kuldip Acharya, Dibyendu Ghoshal, " Variance Value Limited Clipping of Pentile based Sub-histogram Equalization for Contrast Enhancement of Image", International Journal of Image, Graphics and Signal Processing(IJIGSP), Vol.12, No.6, pp. 33-42, 2020.DOI: 10.5815/ijigsp.2020.06.04


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