Impulse noise removal technique considering directional difference of image signal
Yuuhei Hashimoto, Yoshinobu Kajikawa, Yasuo Nomura · Electronics and Communications in Japan (Part III Fundamental Electronic Science) · 2003
Abstract In the problem of restoration of images degraded by impulsive noise, a method has been proposed to eliminate impulsive noise by using the noise position image formed with noise detectors. However, such a method estimates the signal values of the pixels to be processed by using only the nondegraded pixels within the filter window. Hence, if the majority of the window is occupied by impulsive noise, the signal information needed for estimation becomes insufficient and the estimation accuracy is significantly reduced. In addition, in the previous method, average value filters and median filters are used for estimation of the signal value of the processing points. No processing has been included that takes account of the directionality (shape) of image signals such as edge components and detail components. In the present paper, a new noise elimination filter is proposed that attempts to improve restoration accuracy by addressing these two problems. In the proposed filter, first the degraded pixels within the filter window are precompensated for the problem of insufficient original signal pixels in the filter window, and then the signal values at the processing points are estimated by the filter once sufficient signal information is obtained. Preservation of the directionality of the image signals is improved by extending the directional difference filter. Its effectiveness is verified by real image processing results. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 65–75, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ecjc.1149