滤波器（2）: 最大值, 最小值, 低通, 巴特沃斯, Robinson_Guard

 void max_filter(Mat src, Mat dst,int kernalsize)

    
 {
    
 	int ksize;
    
 	if (kernalsize % 2 == 0)
    
 	{
    
 		ksize = kernalsize / 2;
    
 	}
    
 	else
    
 	{
    
 		ksize = (kernalsize - 1) / 2;
    
 	}
    
 	if (kernalsize>src.rows || kernalsize>src.cols)
    
 		cout << "核不合适" << endl;
    
 	//最大值滤波操作
    
 	for (int i = ksize; i < src.rows - ksize; i++)
    
 	{
    
 		for (int j = ksize; j <src.cols - ksize; j++)
    
 		{
    
 			int maxt = 0; //如果是最小值滤波则初始化maxt=255;
    
 			for (int k = i - ksize; k <= i + ksize; k++)
    
 				for (int m = j - ks