Image Steganography using LSB?

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KARTHICK
KARTHICK 2013-3-3
评论： Image Analyst 2024-4-20
I have coded a LSB algorithm for Image Steganography. During retrieval process i'm getting different msg. Can anyone correct this code please!
Embedding code
c = imread('image.bmp');
message = 'hellokarthick'
message = strtrim(message);
m = length(message) * 8;
AsciiCode = uint8(message);
binaryString = transpose(dec2bin(AsciiCode,8));
binaryString = binaryString(:);
N = length(binaryString);
b = zeros(N,1); %b is a vector of bits
for k = 1:N
if(binaryString(k) == '1')
b(k) = 1;
else
b(k) = 0;
end
end
s = c;
height = size(c,1);
width = size(c,2);
k = 1;
for i = 1 : height
for j = 1 : width
LSB = mod(double(c(i,j)), 2);
if (k>m || LSB == b(k))
s(i,j) = c(i,j);
else
if(LSB == 1)
s(i,j) = c(i,j) - 1;
else
s(i,j) = c(i,j) + 1;
end
k = k + 1;
end
end
end
imwrite(s, 'hiddenmsgimage.bmp');
Retriever coding
s = imread('hiddenmsgimage.bmp');
height = size(s,1);
width = size(s,2);
%For this example the max size is 100 bytes, or 800 bits, (bytes * = bits
m = 800;
k = 1;
for i = 1 : height
for j = 1 : width
if (k <= m)
b(k) = mod(double(s(i,j)),2);
k = k + 1;
end
end
end
binaryVector = b;
binValues = [ 128 64 32 16 8 4 2 1 ];
binaryVector = binaryVector(:);
if mod(length(binaryVector),8) ~= 0
error('Length of binary vector must be a multiple of 8.');
end
binMatrix = reshape(binaryVector,8,100);
display(binMatrix);
textString = char(binValues*binMatrix);
disp(textString);
  16 个评论
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Walter Roberson
Walter Roberson 2019-4-5
getframe() takes a copy of whatever has been rendered into the frame, no matter what kind of graphics objects.
getimage() look specifically for image objects, such as created by image() or imagesc() or imshow() . Anything else that is part of the axes will be ignored.

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Walter Roberson
Walter Roberson 2013-3-3
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faiz ul amin
faiz ul amin 2024-4-20
dear walter roberson this is a code that i write for hiding data in 3d image.this code is not complete .i acces the points ,rgb intensity.now i hide the data in rgb intensity .i dont know how to complete code.
Image Analyst
Image Analyst 2024-4-20
@faiz ul amin If you have any questions, then ask them in a new discussion thread (not here), and attach your data and code to read it in with the paperclip icon after you read this:
TUTORIAL: How to ask a question (on Answers) and get a fast answer

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更多回答（11 个）

Maged Rawash
Maged Rawash 2015-4-25
it gives you different msg because you are using JPG and jpg using lossy mode to compress .. which change the pixel value and return different msg ..
you can use that code in imwrite();
imwrite(s,'img.jpg', 'Mode','lossless' );
% not all image application will read JPG lossless
so just work on PNG, TIFF it works with me ...
to retrieve the correct massage without guessing the char number of the massage ... just store the msg length in first pixel and get it in retrieving code like this ....
c = imread(image);
c(1:1:1)= length(msg) ; %to count massage Char to easly retrive all the massage
c=imresize(c,[size(c,1) size(c,2)],'nearest');
message = msg ; %add ' .' to prevint lossing one char
message = strtrim(message);
m = length(message) * 8;
AsciiCode = uint8(message);
binaryString = transpose(dec2bin(AsciiCode,8));
binaryString = binaryString(:);
N = length(binaryString);
b = zeros(N,1);
for k = 1:N
if(binaryString(k) == '1')
b(k) = 1;
else
b(k) = 0;
end
end
s = c;
height = size(c,1);
width = size(c,2);
k = 1;
for i = 1 : height
for j = 1 : width
LSB = mod(double(c(i,j)), 2);
if (k>m || LSB == b(k))
s(i,j) = c(i,j);
elseif(LSB == 1)
s(i,j) = (c(i,j) - 1);
elseif(LSB == 0)
s(i,j) = (c(i,j) + 1);
end
k = k + 1;
end
end
imgWTxt = 'msgimage.png';
imwrite(s,imgWTxt);
----------------------------------- Retriever coding
s = imread(image);
height = size(s,1);
width = size(s,2);
m = double( s(1:1:1) ) * 8 ;
k = 1;
for i = 1 : height
for j = 1 : width
if (k <= m)
b(k) = mod(double(s(i,j)),2);
k = k + 1;
end
end
end
binaryVector = b;
binValues = [ 128 64 32 16 8 4 2 1 ];
binaryVector = binaryVector(:);
if mod(length(binaryVector),8) ~= 0
error('Length of binary vector must be a multiple of 8.');
end
binMatrix = reshape(binaryVector,8,[]);
textString = char(binValues*binMatrix);
disp(textString);
thanks For the Code ...
  5 个评论
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Naveen Gunnam
Naveen Gunnam 2022-3-5
编辑：Naveen Gunnam 2022-3-5
thank you so much dude ,
faiz ul amin
faiz ul amin 2024-4-20
dear walter roberson i need some help.i need code for my project.
project title:data hiddng using 3d image as cover.) i want to hide data in 3d image.

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supriya
supriya 2013-3-10
编辑：supriya 2013-3-10
Actually wat i did is..made an array of the the positions of the pixels whose lsb wud be changed due to the encryption method and then did some changes in ur decryption method..see
c = imread('C:\Documents and Settings\All Users\Documents\My Pictures\Sample Pictures\Sunset.jpg');
message = 'hellokarthick'
message = strtrim(message);
m = length(message) * 8;
AsciiCode = uint8(message);
binaryString = transpose(dec2bin(AsciiCode,8));
binaryString = binaryString(:);
N = length(binaryString);
b = zeros(N,1); %b is a vector of bits
for k = 1:N
if(binaryString(k) == '1')
b(k) = 1;
else
b(k) = 0;
end
end
s = c;
height = size(c,1);
width = size(c,2);
k = 1; Array=[];l=1;my=1;
for i = 1 : height
for j = 1 : width
LSB = mod(double(c(i,j)), 2);
if (k>m || LSB == b(k))
s(i,j) = c(i,j);
l=k+1;
else
if(LSB == 1)
s(i,j) = c(i,j) - 1;
else
s(i,j) = c(i,j) + 1;
Array(my)=l;
l=l+1;
my= my + 1;
end
k = k + 1;
end
end
end
imwrite(s, 'hiddenmsgimage.bmp');
Retriever code changes:
k = 1;my=1;ur=1;
for i = 1 : height
for j = 1 : width
if( k<=m )
if (my<numel(Array) && Array(my)==ur)
b(k)=~(mod(double(s(i,j)),2));
else
b(k) = mod(double(s(i,j)),2);
end
k = k + 1;
my= my + 1;
end
ur=ur+1;
end
end
  9 个评论
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Hammad RIaz
Hammad RIaz 2022-5-2
where to put this code, I need the complete code please. So far Not even a single submitted code worked for me. Can any body provide a single working code along with cover/ sego images please.
Retriever code changes:
k = 1;my=1;ur=1;
for i = 1 : height
for j = 1 : width
if( k<=m )
if (my<numel(Array) && Array(my)==ur)
b(k)=~(mod(double(s(i,j)),2));
else
b(k) = mod(double(s(i,j)),2);
end
k = k + 1;
my= my + 1;
end
ur=ur+1;
end
end
Image Analyst
Image Analyst 2022-5-2
@Hammad RIaz, here is a version to hide text:
https://www.mathworks.com/matlabcentral/fileexchange/54155-encoding-text-into-image-gray-levels?s_tid=srchtitle
and attached is a version for images, and for audio. I know they both work as-is. No guarantees after you start making any modifications of your own.
If you have trouble I suggest you start your own thread and post your code and data.

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ARJUN K P
ARJUN K P 2015-5-16
this code is not actally work correctly.. the extraction text is wrong...pls help me
the output is:
email: arjunkppc@gmail.com
  1 个评论
Image Analyst
Image Analyst 2015-5-16
What's that garbage at the end? Don't paste all that stuff into the command window. Learn how to use a script.

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Mariam Chatha
Mariam Chatha 2016-9-18
how would the code change if we were doing MSB?
  3 个评论
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Shah
Shah 2017-9-17
I need the MATLAB code for MSB hiding text in image stegnography
Image Analyst
Image Analyst 2017-9-18
See my code for hiding in the LSB http://www.mathworks.com/matlabcentral/fileexchange/54155-encoding-text-into-image-gray-levels Of course if you hid it in the most significant bit, that would corrupt the image quite a bit. But nonetheless, you can use it to do that if you want.

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Aishwarya Rajan
Aishwarya Rajan 2016-11-30
Can anyone please explain how the LSB embedding part of the above code works?
Swati Nagpal
Swati Nagpal 2018-7-21
Their is problem with the retrieval code it is showing different unexpected results. So if anyone got the correct result please do share the code. swatinagpal087@gmail.com
Muhammad Asfandyar Shahid
please someone send correct code of image stegnography i will be thankfull
  5 个评论
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Muhammad Asfandyar Shahid
Muhammad Asfandyar Shahid 2018-8-9
ok correct my code and send it back.
Walter Roberson
Walter Roberson 2018-8-9
"ok correct my code and send it back."
No. I posted the link that will get you to a list of over 300 steganography postings. Some of them have complete code, and others have discussions of how you would need to deal with situations such as yours. I have no reason to do your work.

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Souradeep Mukhopadhyay
编辑：Walter Roberson 2021-1-19
% Clear the existing workspace
clear all;
% Clear the command window
clc;
% Read the input image
input = imread('peppers.png');
% Convert image to greyscale
input=rgb2gray(input);
% Resize the image to required size
input=imresize(input, [512 512]);
% Message to be embedded
message='geeksforgeeks';
% Length of the message where each character is 8 bits
len = length(message) * 8;
% Get all the ASCII values of the characters of the message
ascii_value = uint8(message);
% Convert the decimal values to binary
bin_message = transpose(dec2bin(ascii_value, 8));
% Get all the binary digits in separate row
bin_message = bin_message(:);
% Length of the binary message
N = length(bin_message);
% Converting the char array to numeric array
bin_num_message=str2num(bin_message);
% Initialize output as input
output = input;
% Get height and width for traversing through the image
height = size(input, 1);
width = size(input, 2);
% Counter for number of embedded bits
embed_counter = 1;
% Traverse through the image
for i = 1 : height
for j = 1 : width
% If more bits are remaining to embed
if(embed_counter <= len)
% Finding the Least Significant Bit of the current pixel
LSB = mod(double(input(i, j)), 2);
% Find whether the bit is same or needs to change
temp = double(xor(LSB, bin_num_message(embed_counter)));
% Updating the output to input + temp
output(i, j) = input(i, j)+temp;
% Increment the embed counter
embed_counter = embed_counter+1;
end
end
end
% Write both the input and output images to local storage
% Mention the path to a folder here.
imwrite(input, 'path_to_folder\originalImage.png');
imwrite(output, 'path_to_folder\stegoImage.png');
  2 个评论
Walter Roberson
Walter Roberson 2021-1-19
There is a legal distinction between steganography, which "hides" data, and "encryption". If you need to decrypt data then you need to have encrypted it... and we cannot talk about encryption here for legal reasons.

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Hassan Vakani
Hassan Vakani 2021-3-15
I know it is a quite late. First of all thank you for the code. Your logic doesn't have any problem. It is just the placement of the counter which is k=k+1. It should outside the outer if statement and it works.
for i = 1 : height
for j = 1 : width
LSB = mod(double(c(i,j)), 2);
if (k>m || LSB == b(k))
s(i,j) = c(i,j);
else
if(LSB == 1)
s(i,j) = c(i,j) - 1;
else
s(i,j) = c(i,j) + 1;
end
end
k = k + 1;
end
end
imwrite(s, 'hiddenmsgimage.bmp');
No need for adding the b(k) or anything else
PoXiao
PoXiao 2022-3-7
Why did I run Retriever Coding and get garbled code instead of my original string, and how did I extract the original image and display it? I'm really at my wit's end
s = imread('C:\Users\hiddenmsgimage.png');
height = size(s,1);
width = size(s,2);
m = double( s(1:1:1) ) * 8 ;
k = 1;
for i = 1 : height
for j = 1 : width
if (k <= m)
b(k) = mod(double(s(i,j)),2);
k = k + 1;
end
end
end
binaryVector = b;
binValues = [ 128 64 32 16 8 4 2 1 ];
binaryVector = binaryVector(:);
if mod(length(binaryVector),8) ~= 0
error('Length of binary vector must be a multiple of 8.');
end
binMatrix = reshape(binaryVector,8,[]);
textString = char(binValues*binMatrix);
msgbox(textString, 'message');
% disp(textString);
Image Analyst
Image Analyst 2022-3-7
See my attached demo.

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