Extract and embed data bits into image using matlab

2 次查看（过去 30 天）
Willam Willam
Willam Willam 2012-12-25
I got a question want to raise up here. My problem is I want to embed the 2 LSB from each of the character into 2 * 2 matrix and continuous embed until the data is successfully being embed all. But now I cant make it. Your help is really appreciated. Here is my part of the code.
fid = fopen('test.txt'); %open the text file
readText = fread(fid);
fclose(fid); %close the file function
char_in_bit = uint8(readText);
ascii_binary = dec2bin(char_in_bit,7);
size_char = size(char_in_bit); %determine the length of the text file
display(char_in_bit);
display(size_char);
display(BlockRONI);
display(ascii_binary);
for a=1 : size(ascii_binary,1)
for b=1:6
if blocksize==2
n=1;
for r=1:2
for c=1:2
block(r,c)=bitset(block(r,c),1,char_in_bit(n));
n=n+1;
block(r,c)=bitset(block(r,c),2,char_in_bit(n));
%display(block(r,c));
end
end
end
end
block(r,c) = bitset(block(r,c), 7, char_in_bit(n));
end
watermarked_image(y2:y2+blocksize-1, x2:x2+blocksize-1)=block;
watermarked_image_int=uint8(watermarked_image);
imwrite(watermarked_image_int,'watermarked.jpg');
The below data is my input from test.txt file 1010111 1101001 1101100 1101100 1101001 1100001 1101101 and my image that i want embed is gray-scale 8 bit image.
Kindly give me suggestion and appreciate your help
  4 个评论
显示 2更早的评论
Walter Roberson
Walter Roberson 2012-12-26
And what are you getting instead of your expected result?
Willam Willam
Willam Willam 2012-12-29
i want compare the input that i embed is same as the extracted data. But now i manage to embed the data in block size of 2x2. But the extracted data is not compatible to my input. Can sir give me some guides? Thanks

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Image Analyst
Image Analyst 2012-12-26
Why is this line:
block(r,c) = bitset(block(r,c), 7, char_in_bit(n));
outside of your loops over r and c, and even outside of your b loop? Do you know what r and c are then? They're 2, so you're always setting block(2,2).
And what ia A and why should it be all 1's? In your code, what variable take on this/these value(s): "010111 1101001 1101100 1101100 1101001 1100001 1101101 "? Is that char_in_bit? Is it the whole string or just 8 0 and 1 at a time? And what about that sequence of binary numbers means that A should be all 1's?
But my main question is: are you using the debugger to help yourself? Are you stepping through code and examining variables as you go?
  1 个评论
Willam Willam
Willam Willam 2012-12-29
clear all;
global x
global y
global blocksize
global block
global numblock_RONI
global N_RONI
global M_RONI
global startx
global starty
global x2_RONI
global y2_RONI
y2 = 51;
x2 = 31;
cover_object = imread('moon_surface.jpe'); %read the image file
cover_object = double(cover_object);
cover_object = uint8(cover_object);
watermarked_image = cover_object;
%block size
blocksize = 2;
%size of block
N_RONI=50;
M_RONI=50;
%starting point of the pixel
%startx=30;
%starty=50;
%calculate number of block in the RONI
Br_RONI=floor(N_RONI/blocksize); % Blocks per row
Bc_RONI= floor(M_RONI/blocksize); % Blocks per column
numblock_RONI= Br_RONI*Bc_RONI; % number of blocks
display(numblock_RONI);
%display number of block of RONI
BlockRONI=numblock_RONI;
block=cover_object(y2:y2+blocksize-1,x2:x2+blocksize-1);
display(block);
imshow(block);
fid = fopen('test.txt'); %open the text file
readText = fread(fid);
fclose(fid); %close the file function
char_in_bit = double(readText);
display(char_in_bit);
ascii_binary = dec2bin(char_in_bit, 8);
ascii_binary = ascii_binary +0;
size_char = length(char_in_bit); %determine the length of the text file
length = length(ascii_binary);
display(BlockRONI);
%display(class(ascii_binary));
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% Embedding part %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
embed = [];%convert ascii_binary into array form
embed2 = [];
for a1 = 1
embed2 = bitget(ascii_binary, a1);
embed = [embed embed2];
%embed = reshape(embed, [], 8);
%c = mat2cell(b, [], [1 8]);
display(embed);
end
for a=1 : embed
%for b=1:1
n=1;
for r=1:2
for c=1:2
block(r,c)=bitset(block(r,c),1,embed(n));
n=n+1;
block(r,c)=bitset(block(r,c),2,embed(n));
n=n+1;
end
end
end
watermarked_image(y2:y2+blocksize-1, x2:x2+blocksize-1)=block;
% if (x2_RONI+blocksize) > (N_RONI+startx-1)
% if y2_RONI+blocksize < (M_RONI+starty)
% x2_RONI=startx;
% y2_RONI=y2_RONI+blocksize;
% end
% else
% x2_RONI=x2_RONI+blocksize;
%
% end
watermarked_image_int=uint8(watermarked_image);
imwrite(watermarked_image_int,'watermarked.jpg');
display('Done of Embeddding');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% Extract Algorithms %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
cover_object = imread('watermarked.jpg'); %read the image file
cover_object = double(cover_object);
watermarked_image = cover_object;
block=cover_object(y2:y2+blocksize-1,x2:x2+blocksize-1);
retrieveblock = [];
for r=1:2
for c=1:2
retrievebits=bitget(block(r,c),1);
retrieveblock=[retrieveblock retrievebits];
retrievebits=bitget(block(r,c),2);
retrieveblock=[retrieveblock retrievebits];
end
end
display(retrieveblock);
this is the current stage that i do now. But i just curious why my input and my output is totally different? Can sir give me some guides?

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Desktop 的更多信息

标签

尚未输入任何标签。

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by