How to modify the image by applying AES?

fid = fopen('C:\Users\Public\Pictures\Sample Pictures\Desert.jpg', 'r');
data = fread(fid, Inf, '*uint8');
fclose(fid);

After this I apply AES and get the values values. How to use those values and look at the modified image???

[EDIT - MERGED FROM DUPLICATE POST]:

But if I convert this array back to image using image() I do not get the original image.

Even after not performing any changes to the original array that I obtained using the above code...How to get back the original image??

You will probably find it easier to use imread() rather than fread.

How to apply AES algorithm on an image and be able to see the changes by being able to reconvert the array into image????

It's not our place to tell you how to apply the AES encryption algorithm.

Answer 1

image() the resulting array. MATLAB does not care how you created the array that you image()

But if I convert this array back to image I do not get the correct image.

Even after not performing any changes to the original array that I obtained using the above code...How to get back the original image??

Answer 2

There are two different representations, when an image is stored as JPEG:

1. The RGB image data, which can be obtained by imread,
2. The binary JPEG file, which contains a header with meta data also. This is read by fread.

Which one do you want to encode? If you encode the 2nd one, the JPEG file, the result cannot be displayed, because the encoded header is meaningless and does not meet the JPEG format anymore. If you want to store the encoded RGB data as JPEG, be sure to use the mode 'lossless', because even for a 100% Quality rounding errors can change the pixel values slightly. [EDITED, thanks Walter]

So please decide at first, if you want to encode the file or the embedded image.

There is a lossless JPEG mode. Which is not the same as 100% quality (which is not completely lossless.)