Write a function as below which computes a directional first order derivative of 2D Gaussian function: h=dir2dgauss(M, sigma1, N, sigma2, theta).The kernel h is going to have a size of M x N and theta is the angle that the detector is rotated (counte

一个产生2D高斯卷积矩阵的代码，比较简单，很容易明白。-generate the 2D gaussian convolution kernel

Source code for noise median filtering, 2d Gaussian filtering and a Gaussian kernel having a standard deviation and variable size