Apply image kernel on file and create another file

apply_image_kernel.py

from __future__ import division, print_function

import numpy as np
import cv2

COLOR = 1
GRAYSCALE = 0
UNCHANGED = -1


def kernel_transform(input_filename, output_filename):
    img = cv2.imread(input_filename, UNCHANGED)

    N = 5
    kernel_blur = np.ones((N, N), np.float32) / N ** 2

    kernel_deriv = np.array([
        [ 0, 1, 0],
        [ 1,-4, 1],
        [ 0, 1, 0],
    ])

    img = cv2.filter2D(img, -1, kernel_blur)
    img = cv2.filter2D(img, -1, kernel_deriv)

    cv2.imwrite(output_filename, img)


if __name__ == "__main__":
    import sys

    kernel_transform(input_filename=sys.argv[1], output_filename=sys.argv[2])