中值滤波器

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP

在图像处理中，在进行如边缘检测这样的进一步处理之前，通常需要首先进行一定程度的降噪。中值滤波是一种非线性数字滤波器技术，经常用于去除图像或者其它信号中的雜訊。这个设计思想就是检查输入信号中的采样并判断它是否代表了信号，使用奇数个采样组成的观察窗实现这项功能。观察窗口中的数值进行排序，位于观察窗中间的中值作为输出。然后，丢弃最早的值，取得新的采样，重复上面的计算过程。


中值滤波是图像处理中的一个常用步骤，它对于斑点噪声和椒盐噪声来说尤其有用。保存边缘的特性使它在不希望出现边缘模糊的场合也很有用。




目录





  • 1 例子


  • 2 在GIMP中进行中值滤波


  • 3 参考


  • 4 参见


  • 5 外部链接




例子


为了演示中值滤波器的工作过程，我们给下面的数组加上观察窗 3 ，重复边界的数值：


x = [2 80 6 3]


y[1] = Median[2 2 80] = 2

y[2] = Median[2 80 6] = Median[2 6 80] = 6

y[3] = Median[80 6 3] = Median[3 6 80] = 6

y[4] = Median[6 3 3] = Median[3 3 6] = 3


于是

y = [2 6 6 3]


其中 y 是 x 的中值滤波输出。



在GIMP中进行中值滤波


在GIMP 2.8.2中操作如下：


滤镜->增强->去除斑点


不要勾选适应和递归，设置黑色水平为-1，白色水平为256。[1]根据需要调节半径。半径越大，细节越少。







带有椒盐噪声的图像





GIMP中值滤波后的图像（半径为1）



参考




  1. ^ Dossy Shiobara. What is GIMP’s equivalent of Photoshop’s Median filter?. 2007-08-12 [2012-10-10] （英语）. 



参见


  • 噪声

  • 中值

  • 信号处理

  • 数字图像处理


外部链接


  • 中值滤波器

  • 快速二维中值滤波器

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