外文翻译---改进二维中值滤波器在线脉冲噪声的抑制.doc

Improved 2-D Median Filter for On-Line Impulse Noise Suppressiom Abstract-An inproved 2-D median filter employing multishell concept to suppress impulse noise ,is presented.The performance of proposed filter is evaluated over image ‘LENA’ ,The impulsive noise is added using MATLAB utility.The modified strategy reduces the mnuber of replacement and results in better performance and simple hardware realization that is suitable for on-line implementation. Index terms-Median Filter , Multi-shell Median Filter, Impulse Noise I.INTRODUCTION In TV and other imaging systems,impulse noise is a common impairment . The standard T.V.Broadcast signal is often contaminated with impulsive noise arising from various sources such as household electrical appliance and atmospheric disturbances.Broad banding of the signal further increases the level of impulsive noise. Various filters are proposed to suppress such impairments[1].The median filter(MF)[1-2] is widely used for impulse noise suppression and the multishell median filter(MMF)[3] introduces the concept of missing line recovery. Although these filters have satisfactory performance, MMF failsto filter two impulse noises in the same prossing window. Moveover,these filters tend to blur the images due to too many replacements. C.J.Juan proposed a modified multishell median filter (MMMF)[4], which removes most of the shortcomings associated with the MF and the MMF. However, it is observed that under certain condions, to be discussed in the follow sections, MMMF fails to perform the desired filtering operation .Moreover,the number of calculations/replacements invoved on the basis of MIN/MAX conditions is still too large and makes the filter difficult to realize,particulariy for real time applications. In this paper, the threshold strtegy of MMMF is modified so that: effective noise filtering operations are performed under all conditions,and number of calcul