Autosplit Static Diff

import sys
import numpy as np
import cv2

UNIW, UNIH = 320, 240

if len(sys.argv) != 3: raise Exception("Two files should be specified.")
targetFile, captureFile = sys.argv[1:]

# get target, resize, generate mask
target = cv2.imread(targetFile , cv2.IMREAD_UNCHANGED)
if len(target[0][0]) != 4: raise Exception("Image should have 4 channels.")
target = cv2.resize(target, (UNIW, UNIH), interpolation=cv2.INTER_NEAREST)
[lower, upper] = [np.array(bounds, dtype="uint8") for bounds in [[0, 0, 0, 1], [255, 255, 255, 255]]]
mask = cv2.inRange(target, lower, upper)
target = cv2.cvtColor(target, cv2.COLOR_BGRA2BGR)

# get capture, resize
capture = cv2.imread(captureFile, cv2.IMREAD_COLOR)
capture = cv2.resize(capture, (UNIW, UNIH), interpolation=cv2.INTER_NEAREST)

# compare
error = cv2.norm(target, capture, cv2.NORM_L2, mask)    # component-wise norm
normaliser = (3 * np.count_nonzero(mask) * 255 * 255) ** 0.5
result = 1 - (error / normaliser)

print(result)