四、中值滤波平滑方法中值滤波是一种能有效抑制噪声的非线性滤波技术。Tukey建议将它作为分析时间序列的工具,尔后它又被Pratt和Frieden用于图象处理之中。中值滤波器设置一个窗口,将其移遍图象上的各点,且用窗内各原始灰度级的中值代替窗口中心点的原始灰度值。通常这就产生出比原始图象平滑的输出图象。当n为奇数时,n个数x_1,…,x_n的中值就 Fourth, median filtering smoothing method Median filtering is a non-linear filtering technology that can effectively suppress the noise. Tukey suggested using it as a tool for analyzing time series, which was later used by Pratt and Frieden for image processing. The median filter sets a window that moves through the points on the image and replaces the original gray values ​​at the center of the window with the median of the original gray levels in the window. Normally this produces a smoother output image than the original image. When n is an odd number, the median of n numbers x_1, ..., x_n is