Rearrange pixels in image so it can't be recognized and then get it back
Python 2.7 (with PIL) - No Pseudorandomness

I break the image into 2 by 2 blocks (ignoring the remainder) and rotate each block by 180 degrees, then I do the same with 3 by 3 blocks, then 4, etc. up to some parameter BLKSZ. Then I do the same for BLKSZ-1, then BLKSZ-2, all the way back down to 3, then 2. This method reverses itself exactly; the unscramble function is the scramble function.

The code:

from PIL import Image
import math

im = Image.open("ST1.png", "r")
arr = im.load() #pixel data stored in this 2D array

def rot(A, n, x1, y1): #this is the function which rotates a given block
    temple = []
    for i in range(n):
        temple.append([])
        for j in range(n):
            temple[i].append(arr[x1+i, y1+j])
    for i in range(n):
        for j in range(n):
            arr[x1+i,y1+j] = temple[n-1-i][n-1-j]


xres = 800
yres = 480
BLKSZ = 50 #blocksize
for i in range(2, BLKSZ+1):
    for j in range(int(math.floor(float(xres)/float(i)))):
        for k in range(int(math.floor(float(yres)/float(i)))):
            rot(arr, i, j*i, k*i)
for i in range(3, BLKSZ+1):
    for j in range(int(math.floor(float(xres)/float(BLKSZ+2-i)))):
        for k in range(int(math.floor(float(yres)/float(BLKSZ+2-i)))):
            rot(arr, BLKSZ+2-i, j*(BLKSZ+2-i), k*(BLKSZ+2-i))

im.save("ST1OUT "+str(BLKSZ)+".png")

print("Done!")


Depending on the blocksize, you can make the computation eradicate all resemblance to the original image: (BLKSZ = 50)



Or make the computation efficient: (BLKSZ = 10)