import numpy as np
from PIL import Image, ImageOps
from scipy import ndimage

sobel_kernel = np.array([
    [-1, 0, 1],
    [-2, 0, 2],
    [-1, 0, 1],
])

def sobel(arr):
    return ndimage.convolve(arr, sobel_kernel, mode=constant)

def sobel_image(img):
    img = np.array(img)
    return Image.fromarray(sobel(img))