Contrast Enhancement Scheme Integrating Global and Local Contrast Equalization Approaches

2007 ◽  
Author(s):  
Kwanghyun Kim ◽  
Youngjoon Han ◽  
Hernsoo Hahn
Keyword(s):  
Contrast Enhancement ◽  
Local Contrast ◽  
Global And Local

scholarly journals Optimized Contrast Enhancement for Infrared Images Based on Global and Local Histogram Specification

2019 ◽  
Vol 11 (7) ◽  
pp. 849 ◽  
Author(s):  
Chengwei Liu ◽  
Xiubao Sui ◽  
Xiaodong Kuang ◽  
Yuan Liu ◽  
Guohua Gu ◽  
...  
Keyword(s):  
Contrast Enhancement ◽  
Visual Quality ◽  
Local Contrast ◽  
Original Image ◽  
Infrared Images ◽  
Histogram Specification ◽  
Block Based ◽  
Global And Local ◽  
2D Histogram

In this paper, an optimized contrast enhancement method combining global and local enhancement results is proposed to improve the visual quality of infrared images. Global and local contrast enhancement methods have their merits and demerits, respectively. The proposed method utilizes the complementary characteristics of these two methods to achieve noticeable contrast enhancement without artifacts. In our proposed method, the 2D histogram, which contains both global and local gray level distribution characteristics of the original image, is computed first. Then, based on the 2D histogram, the global and local enhanced results are obtained by applying histogram specification globally and locally. Lastly, the enhanced result is computed by solving an optimization equation subjected to global and local constraints. The pixel-wise regularization parameters for the optimization equation are adaptively determined based on the edge information of the original image. Thus, the proposed method is able to enhance the local contrast while preserving the naturalness of the original image. Qualitative and quantitative evaluation results demonstrate that the proposed method outperforms the block-based methods for improving the visual quality of infrared images.

scholarly journals Adaptive Multi-Scale Entropy Fusion De-Hazing Based on Fractional Order

2018 ◽  
Vol 4 (9) ◽  
pp. 108 ◽  
Author(s):  
Uche Nnolim
Keyword(s):  
Contrast Enhancement ◽  
Fractional Order ◽  
Local Contrast ◽  
Multi Scale ◽  
Fully Adaptive ◽  
Color Degradation ◽  
Fractional Filter ◽  
Global And Local ◽  
Enhancement Algorithm ◽  
Experimental Comparisons

This paper describes a proposed fractional filter-based multi-scale underwater and hazy image enhancement algorithm. The proposed system combines a modified global contrast operator with fractional order-based multi-scale filters used to generate several images, which are fused based on entropy and standard deviation. The multi-scale-global enhancement technique enables fully adaptive and controlled color correction and contrast enhancement without over exposure of highlights when processing hazy and underwater images. This in addition to the illumination/reflectance estimation coupled with global and local contrast enhancement. The proposed algorithm is also compared with the most recent available state-of-the-art multi-scale fusion de-hazing algorithm. Experimental comparisons indicate that the proposed approach yields a better edge and contrast enhancement results without a halo effect, without color degradation, and is faster and more adaptive than all other algorithms from the literature.

scholarly journals Adaptive Multi-Scale Entropy Fusion De-hazing based on Fractional Order

2018 ◽  
Author(s):  
Uche A. Nnolim
Keyword(s):  
Contrast Enhancement ◽  
Fractional Order ◽  
Local Contrast ◽  
Multi Scale ◽  
Fully Adaptive ◽  
Local Contrast Enhancement ◽  
Fractional Filter ◽  
Global And Local ◽  
Enhancement Algorithm ◽  
Experimental Comparisons

This paper describes a proposed fractional filter-based multi-scale underwater and hazy image enhancement algorithm. The proposed system combines a modified global contrast operator with fractional order-based multi-scale filters used to generate several images, which are fused based on entropy and standard deviation. The multi-scale-global enhancement technique enables fully adaptive and controlled colour correction and contrast enhancement without over exposure of highlights when processing hazy and underwater images. This in addition to illumination/reflectance estimation coupled with global and local contrast enhancement. The proposed algorithm is also compared with the most recent available state-of-the-art multi-scale fusion de-hazing algorithm. Experimental comparisons indicate that the proposed approach yields better edge and contrast enhancement results without halo effect, colour degradation and is faster and more adaptive than all other algorithms from the literature.

scholarly journals Clinical evaluation of ‘local contrast enhancement’ for oral fluorescein angiograms

Eye ◽  
2000 ◽  
Vol 14 (3) ◽  
pp. 318-318 ◽  
Author(s):  
Richard S B Newsom ◽  
Chanjira Sinthanayothin ◽  
James Boyce ◽  
Anthony G Casswell ◽  
Tom H Williamson
Keyword(s):  
Contrast Enhancement ◽  
Clinical Evaluation ◽  
Local Contrast ◽  
Local Contrast Enhancement
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