Histogram statistics based variance controlled adaptive threshold in anisotropic diffusion for low contrast image enhancement

  • Authors:
  • Uddin Khan Nafis;K. V. Arya;Manisha Pattanaik

  • Affiliations:
  • ABV-Indian Institute of Information Technology and Management, Morena Link Road, Gwalior 474015, India;ABV-Indian Institute of Information Technology and Management, Morena Link Road, Gwalior 474015, India;ABV-Indian Institute of Information Technology and Management, Morena Link Road, Gwalior 474015, India

  • Venue:
  • Signal Processing
  • Year:
  • 2013

Quantified Score

Hi-index 0.08

Visualization

Abstract

It is very difficult in low contrast images to distinguish between the noisy background and the regions of low gray level inter-region edges. The classical Perona-Malik anisotropic diffusion is able to smooth the defective background but cannot enhance faultless low gray level inter-region edges in such low contrast images. The proposed method provides an unsupervised machine learning process to modify the anisotropic diffusion by generating an adaptive threshold in diffusion coefficient function using statistical measures. In the proposed method, image histogram is employed to calculate the global gray level variance over the entire image and local gray level variance over the defined neighborhood of each pixel of given image. The adaptive threshold in diffusion coefficient function varies in accordance with the difference between the two variances which gives a measure of intensity contrast in that neighborhood. The experimental results from various low contrast images have shown that the proposed unsupervised machine learning approach for adaptive threshold selection in anisotropic diffusion can effectively smooth noisy background with preservation of low gradient edges.