Random shuffle of image pixels/ Image scrambling

hello,

I am applying arnold transform method on an image to scramble its pixels. And i am doing it successfully but the problem in this method is that first I have to binarize the image before applying this method and that is why I am getting binarized image in a result in inverse of arnold transform. So, my question is that is there any other method in which I scramble or shuffle pixels by setting a key value without binarizing the image? so that I would be able to revert the image back ?

thank you very much :-)

Answer 1

[Sindar]

You can use randperm to shuffle the indices randomly, then sort to get the indices for reversing it:

% load in an image included in Matlab
corn_gray = imread('corn.tif',3);
% get the size
imsize = size(corn_gray);
% display
imshow(corn_gray)

% create a randomly-shuffled list of linear indices 1:total pixels
idx_shuffle=randperm(numel(corn_gray));
% get the inverse (idx_shuffle(idx_unshuffle) = 1:total pixels)
[~,idx_unshuffle] = sort(idx_shuffle);
% put the indices into the same row-col shape as the image
idx_shuffle = reshape(idx_shuffle,imsize);
idx_unshuffle = reshape(idx_unshuffle,imsize);
% compute the shuffled image
corn_gray_shuffled = corn_gray(idx_shuffle);
% run an arbitrary transformation on it
corn_gray_shuffled = corn_gray_shuffled.^2;
% display the shuffled, transformed image
imshow(corn_gray_shuffled)

% unshuffle the transformed image
corn_gray_unshuffled = corn_gray_shuffled(idx_unshuffle);
% and display
imshow(corn_gray_unshuffled)

[Sindar]

rereading you question, I'm not sure if this will actually help directly. But, maybe it will give you some ideas, or help people brought here by the title

[marie lasz]

thanks for your response but I need a method which scrambles the image pixels with number of iterations and that method can also does an inverse transform to its original image.

[Faizan Ahmed Khan]

@marie lasz did you find how we can do this ?

[marie lasz]

@Faizan, No I didn't. But I am working with Arnold.