Contrast enhancement of bimodal SAR images using a new desired histogram method with Gamma distribution

  • Authors:

  • Ali El-Zaart

  • Affiliations:

  • Department of Computer Science, College of Computer and Information Sciences, King Saud University, P.O. Box 51178, Riyadh, 11543, Kingdom of Saudi Arabia

  • Venue:
  • International Journal of Internet Technology and Secured Transactions
  • Year:
  • 2009

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Abstract

The technique of image histogram modification can be applied to the problem of image enhancement. Global and local histogram equalisation and local area histogram equalisation are two well-known techniques for the same purpose. In this research work, a new method is proposed to enhance the contrast of bimodal SAR images using histogram specification with Gamma distribution. The method is aimed to read the original image and calculate its original histogram. Then apply the maximum likelihood with Gamma distribution (ML) technique on the original histogram to get accurate statistical parameters as the means and prior probabilities of the two modes. The two estimated modes are thus separated by shifting the first mode to the left or shifting the second mode to the right or performing both shifts. After shifting, a new histogram called 'desired histogram' is generated from a mixture of Gamma distributions using updated data. By applying a histogram specification method, a high contrast SAR image will be produced. The new method of contrast enhancement of SAR image has been applied on bimodal SAR images and showed good results.