MATLAB Answers

0

hide numerical values in image

Elysi Cochin さんによって質問されました 2019 年 2 月 23 日
最新アクティビティ Elysi Cochin さんによって コメントされました 2019 年 2 月 28 日
how to hide a matrix into an image and retrieve it.
i used the lsb code from the link
i can hide the data. But while retrieving i'm not able to recover the matrix values. Its coming as empty string values. Even the bitStream values when i convert to double is not coming correctly
How can i do it for numerical values.

  0 件のコメント

サインイン to comment.

1 件の回答

Image Analyst
回答者: Image Analyst
2019 年 2 月 23 日
 採用された回答

See my attached demo where I hide an image in another image and then recover it.

  13 件のコメント

Elysi Cochin 2019 年 2 月 27 日
Sir @Walter Roberson,
You have asked me exactly what i wanted
"Suppose I somehow hide a complete 768 x 480 grayscale image of The Mona Lisa into a cover image. Now suppose I crop down to one single pixel. Should I expect to be able to recover the complete Mona Lisa from the cropped image?"
Yes, sir i should be able to recover it. I was asking this only, whether there is any method available.
Then as you said
"You expect to be able to recover the complete Mona Lisa, so the complete Mona Lisa has to be hidden in the left half of the original... hide the Mona Lisa four times, once for each quarter"
Sir, i was asking this only, whether there is any method so that i can hide my 2 images in any 2 quarter, and crop from other 2 quarters. Actually cropping from anywhere should not effect it. But is there any method where "i can hide my 2 images in any 2 quarter"
I opted for this tiff method because i didnt get a solution for hiding my 2 images of same size as cover image in the cover image. If any solution for saving it in quarter, it would be very helpful
Then from the tiff method, i did as below.
im = imread('subimage_file.tif');
im(50:100,50:100,:) = 255;
imwrite(im, 'subimage_file.tif');
But when i do then i cannot read the subdirectory images in the tiff image. Any solution for this? Or should i write it the other way using Tiff class then only i can read it?
Image Analyst
2019 年 2 月 27 日
Elysi, as long as you don't crop off what you stored, you should be able to recover it. That is if you were able to store it. And storing two quarter sized full dynamic range images in a regular image without seeing it is not possible. You might try hiding an 8 bit image in the lower 8 bits of a 16 bit image.
And you'd need to use the tiff class to have any hope of storing a custom tag, but when your attacker reads it in, there is no guarantee that they will save your tag, in fact, probably won't, just like using imwrite() won't. So it would be easy for your attacker to read in, attack, and save back out, and then you would not be able to tell that that image was your forged/attacked image because your custom tiff tag if no longer there.
Elysi Cochin 2019 年 2 月 28 日
Thank you Image Analyst and Walter Roberson for your detailed explanation

サインイン to comment.



Translated by