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image_scrambling.py
149 lines (114 loc) · 4.03 KB
/
image_scrambling.py
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import numpy as np
from PIL import Image
import random
from typing import List
class ImageScramble(object):
"""Image Scrambling using Pillow Image.
Reference:
https://stackoverflow.com/questions/17777760/mixing-pixels-of-an-image-manually-using-python
"""
@staticmethod
def _set_seed_from_image(img: np.ndarray) -> None:
"""画像からハッシュ値を計算し，シードを設定する．
ハッシュ値は，画像スクランブルの前後で変わってはいけない．
今回はRGBそれぞれの画素値の平均からハッシュ値を算出した．
Args:
img (np.ndarray): input image
"""
# use RGB mean value to calculate hash value
average = np.mean(img.reshape(-1, 3), axis=0)
average = tuple(average)
random.seed(hash(average))
@staticmethod
def _get_pixels(img: np.ndarray) -> np.ndarray:
"""Get the list of pixel values
Args:
img (np.ndarray): (h, w, 3)
Returns:
np.ndarray: (h*w, 3)
"""
pixels = img.reshape(-1, 3)
return pixels
@staticmethod
def _restore_image(
pixels: np.ndarray, original_width: int, original_height: int
) -> np.ndarray:
"""Restore an image from the list of pixel values
Args:
pixels (np.ndarray): (h*w, 3)
original_width (int): the width of an original image
original_height (int): the height of an original image
Returns:
np.ndarray: (h, w, 3)
"""
img = pixels.reshape((original_height, original_width, 3))
return img
@staticmethod
def _scramble_index(pixels: np.ndarray) -> List[int]:
"""Scramble indicies of pixels.
Args:
pixels (np.ndarray): (h*w, 3)
Returns:
List[int]: shuffled index list
"""
idx = list(range(len(pixels)))
random.shuffle(idx)
return idx
def _scramble_pixels(self, img: np.ndarray) -> np.ndarray:
"""Scramble pixels
Args:
img (np.ndarray): (h, w, 3)
Returns:
np.ndarray: (h*w, 3)
"""
pixels = self._get_pixels(img)
idx = self._scramble_index(pixels)
scrambled_pixels = pixels[idx]
return scrambled_pixels
def scramble(self, img: Image.Image) -> Image.Image:
"""Do image scrambling.
Args:
img (Image.Image): input image
Returns:
Image.Image: scrambled image
"""
w, h = img.size
img = np.asarray(img)
self._set_seed_from_image(img)
scrambled_pixels = self._scramble_pixels(img)
img = self._restore_image(scrambled_pixels, w, h)
return Image.fromarray(img)
def _unscramble_pixels(self, img: np.ndarray) -> np.ndarray:
"""Unscramble pixels
Args:
img (np.ndarray): (h, w, 3)
Returns:
np.ndarray: (h*w, 3)
"""
pixels = self._get_pixels(img)
idx = self._scramble_index(pixels)
# argsortを使って元画像のピクセルのインデックスを取得する
idx = np.argsort(idx)
original_pixels = pixels[idx]
return original_pixels
def unscramble(self, img: Image.Image) -> Image.Image:
"""Do unscramgling image
Args:
img (Image.Image): input scrambled image.
Returns:
Image.Image: unscrambled image.
"""
w, h = img.size
img = np.asarray(img)
self._set_seed_from_image(img)
original_pixels = self._unscramble_pixels(img)
img = self._restore_image(original_pixels, w, h)
return Image.fromarray(img)
if __name__ == "__main__":
image_path = "../imgs/2007_000032.jpg"
img = Image.open(image_path)
processor = ImageScramble()
scrambled_img = processor.scramble(img)
scrambled_img.save("scrambled.jpg")
unscrambled_img = processor.unscramble(scrambled_img)
unscrambled_img.save("unscrambled.jpg")