from PIL import Image
from operator import xor

input = "dungeons_portal_enc.png"

input_image = Image.open(input)
width, height = input_image.size

sample_size = 50
offset = 400
# output_image = Image.new(input_image.mode, (int(sample_size), int(sample_size)))
# for N in range(0,256):
#     for x in range(offset, offset+sample_size):
#         for y in range(offset, offset+sample_size):
#             pixel = input_image.getpixel((x,y))
#             if xor((x**3+y**7)%256, N)%256 == pixel:
#                 output_image.putpixel((x-offset,y-offset), 0)
#             else:
#                 output_image.putpixel((x-offset,y-offset), 255)

#    output_image.save(f"d_{N:04}.png")

#==>N semble valoir 7

N = 7
output_image = Image.new(input_image.mode, (int(width), int(height)))

for x in range(width):
    for y in range(height):
        pixel = input_image.getpixel((x,y))
        if xor((x**3+y**7)%256, N)%256 == pixel:
            output_image.putpixel((x,y), 0)
        else:
            output_image.putpixel((x,y), 255)

output_image.show()