Scramble-Unscramble - Shuffles images into fixed size patches to create a jigsaw puzzle.A key-map dictionary is used to recover the shuffled image.

image_scramble.py

import numpy as np
from PIL import Image
from imageio import imsave
from skimage.util.shape import view_as_blocks

# Global shuffle key
map={}

'''
Args:-
im: Image to be shuffled (square shape)
num: number of rows = columns 
inverse: shuffle or inverse-shuffle
'''
def shuffle(im, num, inverse = False):
  global map
  rows=cols=num
  blk_size=im.shape[0]//rows # patch size

  # Create an array of num*num elements of size (blk_size,blk_size,3)
  img_blks=view_as_blocks(im,block_shape=(blk_size,blk_size,3)).reshape((-1,blk_size,blk_size,3))
  
  # Initialize output array
  img_shuff=np.zeros((im.shape[0], im.shape[0],3),dtype=np.uint8)
 
  # Create a random shuffle key
  a=np.arange(rows*rows, dtype=np.uint8)
  b=np.random.permutation(a)

  if(inverse):
      inv_map = {v: k for k, v in map.items()}
      print("Inverse Map:-\n" + str(inv_map)) 

  else:
      map = {k:v for k,v in zip(a,b)}
      print("Key Map:-\n" + str(map))
  
  # Shuffle the image according to key
  for i in range(0,rows):
    for j in range(0,cols):
     x,y = i*blk_size, j*blk_size
     if(inverse):
      img_shuff[x:x+blk_size, y:y+blk_size] = img_blks[inv_map[i*rows + j]]
     else:
      img_shuff[x:x+blk_size, y:y+blk_size] = img_blks[map[i*rows + j]] 
  return img_shuff
 
# Input RGB image
im=np.array(Image.open('angrybird.jpeg').convert('RGB'))
shuff=shuffle(im,7, inverse=False)
reverted=shuffle(shuff,7, inverse=True)

# Output RGB images
imsave("scramble.png",shuff)
imsave("unscramble.png",reverted)