Tool to instasolve ctf chals that involve finding colour differences of like 1 shade in rgb

differ.py

import numpy as np
from PIL import Image
import sys

def shift_and_xor(image_path, output_path, threshold):
    img = Image.open(image_path)
    img_array = np.array(img)
    shifted = np.zeros_like(img_array)
    shifted[1:, 1:] = img_array[:-1, :-1]
    result = img_array ^ shifted
    result_gray = np.dot(result[..., :3], [1/3, 1/3, 1/3])
    result_binary = (result_gray > threshold).astype(np.uint8) * 255
    result_img = Image.fromarray(result_binary)
    result_img.save(output_path)
    print(f"Saved to {output_path}")


if len(sys.argv) != 4 and len(sys.argv) != 3:
    print("Usage: [input] [output] [threshold (default = 30)]")
elif len(sys.argv) == 4:
    shift_and_xor(sys.argv[1], sys.argv[2], int(sys.argv[3]))
else:
    shift_and_xor(sys.argv[1], sys.argv[2], 30)