Modified Hybrid Median Filter for Removal of Low Density Random-Valued Impulse Noise in Images

Random-valued impulse noise (RVIN) is a randomly distributed noise of two significant pixel values that degrades the quality of digital images during acquisition, processing, and storage. It is a variation of the salt-and-pepper or fixed-valued impulse noise (FIN) which instead of the black and white pixel, the noisy pixel value can be anywhere in the range of the grey level pixel. This paper introduces a new filter which is a modified hybrid median filter for removal of RVIN from digital images. The proposed filter is based on similar standard median filters and an improvement upon the hybrid median filter which make use of neighborhood pixels in reducing RVIN from the image. This filter operates using a window size of 3x3 and uses values in the window with a modified hybrid median algorithm to replace the targeted pixel during the filtering process. This technique has proven to be capable of overcoming the shortcomings of standard median filter as well as improve upon the hybrid median filter in restoring image details and in operating at higher noise density.