import numpy as np

def gaussian2D(shape=(2500,250), sigma=100):
    m, n = [(ss - 1.) / 2. for ss in shape]
    y, x = np.ogrid[-m:m+1,-n:n+1]

    h = np.exp(-(x * x + y * y) / (2 * sigma * sigma))
    h[h < np.finfo(h.dtype).eps * h.max()] = 0
    return h
