Efficient Algorithm for Contrast Enhancement
 of Natural Images

Shyam Lal1 and Mahesh Chandra2
1ECE Department, Moradabad Institute of Technology, Moradabad (U.P.), INDIA
2ECE Department, Birla Institute of Technology, Mesra, Ranchi (J.H.), INDIA

Abstract: This paper proposed an efficient algorithm for contrast enhancement of natural images. The contrast of image is very important characteristics by which the quality of image can be judged as good or poor quality. The proposed algorithm is consists of two stages: In first stage the poor quality of image is process by modified sigmoid function  and in second stage the output of first stage is further process by contrast limited adaptive histogram equalization to enhance contrast of image. In order to achieve better contrast enhancement of image a novel mask based on input value together with the modified sigmoid formula that will be used as contrast enhancer in addition to contrast limited adaptive histogram equalization. This new contrast enhancement algorithm passes over the input image which operates on its pixels one by one in spatial domain. Simulation & experimental results on benchmark test images demonstrates that proposed algorithm provides better results as compared to other state-of-art contrast enhancement techniques. Proposed algorithm performs efficiently in different dark and bright images by adjusting their contrast very frequently. Proposed algorithm is very simple and efficient approach for contrast enhancement of image. This algorithm can be used in various applications where images are suffering from different contrast problems.

Keywords: Contrast enhancement, Modified sigmoid function, Image processing, Histogram equalization.

 

Received April 21, 2012; accepted August 10, 2012

  

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