ある画像をいくつかのブロックに分割し、ランダムに並び替えたい時

random_grid_shuffle.py

import numpy as np
import matplotlib.pyplot as plt
import cv2
import random

img = cv2.imread('img.jpg')
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)


def concat_tile(im_list_2d):
    return cv2.vconcat([cv2.hconcat(im_list_h) for im_list_h in im_list_2d])


def tile_flip(tile):
    """
    random flip
    """
    tmp = np.random.randint(4)
    if tmp==0:
        return tile
    elif tmp==1:
        return tile[::-1, :, :]
    elif tmp==2:
        return tile[:, ::-1, :]
    else:
        return tile[::-1, ::-1, :]


def tile_shuffle(img, num=2):
    """
    img: input image
    N: number of blocks
    """
    H, W, _ = img.shape
    imgs = [[] for _ in range(num)]
    row = 0

    for i in random.sample(list(range(num)), num):
        for j in random.sample(list(range(num)), num):
            h = i*(H//num)
            w = j*(W//num)
            tmp = img[h : h+H//num, w : w+H//num, :]
            tmp = tile_flip(tmp)
            imgs[row].append(tmp)
        row += 1
    shuffle = concat_tile(imgs)

    return shuffle