Need help to scramble unscramble gray scale image based on Affine Transformation

Hi,

I am trying gray scale image affine transformation but after doing scramble, unscramble is not happening. PFB the source code. Need help urgently please.

% To read rgb image and covert that to gray scale 128*128

a = imread('C:/Matlab/image1.jpg');

b = rgb2gray(a);

c = imresize(b,[128,128]);

imwrite(c,'C:/Matlab/resized.jpg');

inImg = double(imread('C:/Matlab/resized.jpg'));

%s = size(inImg);

%enImg = ones(s);

img = inImg(:,:,1);

[i, j] = size(img);

%subplot(1,4,1);

%imshow(img);

%To scramble

[y, x] = ndgrid(1:size(img, 1), 1:size(img, 2)); %order is [y, x] or [row, column]

f1 = floor((3 + 13 * x) / 128);

x1 = mod(3 + 13 * x, 128);

f2 = floor((5 + 7 * y) / 128);

y1 = mod(5 + 7 * y, 128);

scrambledimage = img(sub2ind(size(img), y1+1, x1+1));

%subplot(1,4,2);

%imshow(scrambledimage);

imwrite(scrambledimage,'C:/Matlab/scrambledimage.jpg');

%To unscramble

newx = mod(((x1 + (f1 * 128)) - 3) / 13, 129);

newy = mod(((y1 + (f2 * 128)) - 5) / 7, 129);

for k = 1 : numel(newx)

newRow = round(newy(k));

newCol = round(newx(k));

%enImg(newRow, newCol) = scrambledimage(y1(k)+1, x1(k)+1);

enImg(newRow, newCol) = scrambledimage(sub2ind(size(scrambledimage), y1(k)+1, x1(k)+1));

end

%subplot(1,4,3);

%imshow(newR);

imwrite(enImg,'C:/Matlab/unscrambledimage.jpg');