Thats a sample .png image
plt.imshow(img)
Out[10]: <matplotlib.image.AxesImage at 0x1288d4da0>

img.size
Out[12]: (512, 512)
np.unique(np.array(img))
Out[13]: array([2, 3, 5, 6, 7, 8, 9], dtype=uint8)