Gaussian image noise

import cv2
import numpy as np
import math
 
def gaussian_noise_add(img):
 
    height, width, depth = np.shape(img)
 
    n_50 = np.random.normal(0, 50, [height, width, depth])
 
    noisy = (img + n_50).clip(0, 255)
 
    return noisy
 
 
if  __name__ == "__main__":
 
    img = cv2.imread("Lenna.jpg")
 
    noisy_img = gaussian_noise_add(img)
 
    cv2.imwrite("Lenna_gaussian_noise.jpg", noisy_img)