Pillow - substract images to find differences

from PIL import Image, ImageChops
import numpy as np

FOLDER = '/home/username/'
img1 = Image.open(FOLDER + 'image1.png').convert('RGB') # without A (RGBA) to remove transparency
img2 = Image.open(FOLDER + 'image2.png').convert('RGB') # without A (RGBA) to remove transparency

diff = ImageChops.difference(img2, img1).convert('L') # L = grayscale (it will covert three numbers R,G,B into one number)
diff.save(FOLDER + 'diff.png')

arr = np.asarray(diff) # convert to numpy's array
data = np.nonzero(arr) # find nonzero values

for x, y  in zip(data[0], data[1]):
    print(x, y)