Rank-Ordered Statistic based different Median Filters for eliminating Impulse Noise in Images

Eliminating of impulse noise from images without losing their features is an important requirement in image processing applications. The standard median filter is a good nonlinear filter for eliminating impulse noise; however, it fails to preserve the image details when the window size is made larger. In this paper, three nonlinear filtering schemes, based on Rank-Ordered Logarithmic Difference image statistic, are introduced for cleaning the images confounded by impulse noise. These ROLD based nonlinear filtering techniques perform the filtering function on the basis of sum of rankordered logarithmic differences between central pixel inside the window and its neighboring pixels. Extensive simulation studies have been carried out by applying the proposed filtering schemes on a test image corrupted with different levels of impulse noise and the results obtained are included. Keywords— image statistics, impulse detection, impulse noise and Median filter, ROLD and order-statistics.