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A Comparison of Contrast Enhancement Techniques in Poor Illuminated Gray Level and Color Images

Author(s): Narasimhan K | Sudarshan C R | Nagarajan Raju

Journal: International Journal of Computer Applications
ISSN 0975-8887

Volume: 25;
Issue: 2;
Start page: 17;
Date: 2011;
Original page

Keywords: Image acquisition | Optimization problem | DCT | Webers law

Morphological transformations 'Opening by reconstruction, ErosionDilation method' and Block Analysis is used to detect the background of gray level and color images. These techniques are first implemented in gray scale and are then extended to color images by individually enhancing the color components. For aiding better results, the compressed domain 'DCT' technique is used exclusively for color image enhancement. The major advantage of the DCT method is that it can be used for any type of illumination. In all the above methods, the enhancement of the background detected image is done using Webers law 'modified Webers law for compressed domain'. In this paper, a critical analysis of the various advantages and drawbacks in each method are performed and ways for overcoming the drawbacks are also suggested. Here, the results of each technique are illustrated for various backgrounds, majority of them in poor lighting condition. The tool used in this study is MATLAB. Finally the performance metrics like Entropy, Color Enhancement Factor 'CEF' , JPEG Quality Metric 'JPQM' , Wang Bovik Quality metric 'WBQM' and Structural Similarity Index 'SSIM' are calculated and compared for the results of each technique.
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