Speckle image noise

import cv2
import numpy as np
import math
 
def Speckle_noise_add(img):
 
    row, col, depth = np.shape(img)
 
    mean = 0
 
    var = 0.1
 
    gauss = np.random.normal(mean, math.sqrt(var), (row, col, depth))
 
    noisy = img + img * gauss
 
    noisy = np.array(noisy, dtype=np.uint8)
 
    return noisy
 
 
if  __name__ == "__main__":
 
    img = cv2.imread("Lenna.jpg")
 
    noisy_img = Speckle_noise_add(img)
 
    cv2.imwrite("lena_speckle_noise.jpg", noisy_img)