I did PVD steganography for hiding text in color image can any one please help me to use the same code for hiding color image inside color cover image in matlab?

I did PVD steganography for hiding text in color image can any one please help me to use the same code for hiding color image inside color cover image in matlab? The code for hiding text inside color cover image and extracting from it is given below.

clc;

close all;

clear;

%%%%%%%%%%%%%%%%%%%%%%%Reading a Secret Text File %%%%%%%%%%%%%%%%%%%%%%%%

file_id = fopen('message.txt','r');

file_content = fread(file_id);

file_length = length(file_content);

in = [];

in = [in dec2bin(file_length,20)]; %character to binary conversion 

for i=1:file_length  

      in=[in dec2bin(file_content(i),7)];

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%Reading Cover Image %%%%%%%%%%%%%%%%%%%%%%%%%%%

cover_image = imread('cover_image.bmp'); %get cover image      

red = cover_image(:,:,1); %seperating rgb values 

blue = cover_image(:,:,2);

green = cover_image(:,:,3);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Embedding Data %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
color = red; %red color selected for embedding

[r,c] = size(color);

final = double(color); 

next=0;

capacity=0; %total no of bits that can be embedded

for x=0:1:r-1 

      for y=0:2:c-1

          enable = 1; %enable=0 when new pixels may fall off the boundary

          p = color(1+x,1+y:2+y); %block of two pixels, pi & pi+1

          p = double(p);

          d = p(1,2) - p(1,1); %d = difference between 2 pixel

          d_abs = abs(d); %absolute difference

          lb=[0 8 16 32 64 128]; %lowerbound

          ub=[7 15 31 63 127 255]; %upperbound

          for i=1:1:6 %test the R boundary

              if((d_abs >= lb(i)) && (d_abs <= ub(i))) %selecting range

                  %check if any pixel in a block fall off the boundary [0,255]

                  even2 = mod(d,2); 

                  m2 = ub(i) - d;

                  if (even2 == 0)

                      Pcheck=[p(1,1)-floor(m2/2) p(1,2)+ceil(m2/2)];

                  else

                      Pcheck=[p(1,1)-ceil(m2/2) p(1,2)+floor(m2/2)];

                  end

                  if(Pcheck(1)<0 || Pcheck(2)<0 || Pcheck(1)>255 || Pcheck(2)>255)

                      enable = 0;

                      break

                  end

                  n = ub(i)-lb(i)+1; %quantization width of range

                  t = floor(log2(n)); %maximum bit can be embedded in 2 pixels

                  capacity=capacity+t; %max capacity of the cover image 

                  %check if next exceeds the length of message
                  if(next>length(in)) 

                      m=0;

                  %check if next+t exceeds the length of message

                  elseif(next+t>length(in)) 

                      if(1+next>=length(in))

                          k=zeros(1,t);

                      else

                          k=in(1+next:length(in));

                      end

                      diff =next+t-length(in);

                      k1=zeros(1,t);

                      if(diff>0)

                          for j=1:next+t-length(in)

                              k1(j)=k(j);

                          end

                      end

                      k=k1;

                      next=next+t;

                      k=bin2dec(char(k));

                      if(1+next>length(in))

                          m=0;

                      else

                          if(d >= 0)

                              dnew = k + lb(i);

                          else

                              dnew = -(k + lb(i));

                          end

                          m = dnew - d;

                      end

                  %if next is less than the length of message
                  else 

                      k=in(1+next:t+next);

                      next=next+t;

                      k=bin2dec(char(k));

                      if(d >= 0)

                          dnew = k + lb(i);

                      else

                          dnew = -(k + lb(i));

                      end

                      m = dnew - d;

                  end

              end
          end

          if (enable == 1)

              even = mod(d,2);

              if (even == 0)

                  P0=[p(1,1)-floor(m/2) p(1,2)+ceil(m/2)];

              else

                  P0=[p(1,1)-ceil(m/2) p(1,2)+floor(m/2)];

              end

              final(1+x,1+y)=P0(1,1);

              final(1+x,2+y)=P0(1,2);

          end

      end
  end
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%Creating Stego-Image %%%%%%%%%%%%%%%%%%%%%%%%%%

if(next>length(in))

      disp('Message Embedded Successfully');

      final = uint8(final);

      stego_image = cat(3,final,blue,green);

      imwrite(stego_image,'stego_image.bmp');
      fclose('all');
  else %check if the cover is samll for the given messege to be embedded
      error('Cover Image is too small for the given messege to be embedded, please replace cover image with the larger one.');
  end
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

clc;
clear all;

%%%%%%%%%%%%%%%%%%%%%%%%%%%Reading Stego Image %%%%%%%%%%%%%%%%%%%%%%%%%%%

stego_image = imread('stego_image.bmp');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Extracting Data %%%%%%%%%%%%%%%%%%%%%%%%%%%%

color = stego_image(:,:,1); %red color selected where data is embedded

[r,c]=size(color);

j=0;

msg = [];

flag = 0;

length=0;

enable = 1;

for x=0:1:r-1

      for y=0:2:c-1

          if (enable == 1) %enable=0 when any pixels may fall off the boundary

              gp = color(1+x,1+y:2+y); %block of 2 pixels, pi & pi+1

              gp = double(gp);

              d  = gp(1,2) - gp(1,1); %d = difference between 2 pixel

              nd = abs(d); %absolute difference

              lb = [0 8 16 32 64 128]; %lowerbound

              ub = [7 15 31 63 127 255]; %upperbound

              for i=1:1:6 %test the R boundary

                  if(nd>=lb(i)&&nd<=ub(i))

                      %check if any pixel in a block fall off the boundary [0,255]

                      even2 = mod(d,2); 

                      m2 = ub(i) - d;

                      if (even2 == 0)

                          Pcheck=[gp(1,1)-floor(m2/2) gp(1,2)+ceil(m2/2)];

                      else

                          Pcheck=[gp(1,1)-ceil(m2/2) gp(1,2)+floor(m2/2)];

                      end

                      if(Pcheck(1)<0 || Pcheck(2)<0 || Pcheck(1)>255 || Pcheck(2)>255)

                          break

                      end

                      w = ub(i)-lb(i)+1; %quantization width of range
                      t=log2(w); %maximum bit can be embedded between 2 pixel
                      b = nd - lb(i);
                      k=dec2bin(b,t);
                      msg = [msg k];
                      j=j+t;

                      if(flag==0 && j>=20)
                          length=bin2dec(msg(1:20))+3; %possible 3 char error
                          length=length*7;
                          flag=1;
                      end

                      if(flag==1 && j>=length)
                          j=1;
                          for i=20:7:length-7
                              finaltxt(j)=bin2dec(msg(1+i:7+i));
                              j=j+1;
                          end
                          fid=fopen('output.txt','w');
                          fwrite(fid,finaltxt);
                          disp('Message Extracted Successfully');
                          fclose('all');
                          enable = 0;
                      end

                  end
              end
          end
      end
  end
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[A A]

hi , can you help me please , my project it about hiding secret message in an image , I find the code valid for me, but do not know why do not implement with me, please can you help thanks

[Walter Roberson]

A A: please see https://www.mathworks.com/matlabcentral/answers/?term=tag%3A%22steganography%22 as there are many posts on the topic, some of which contain complete code.

Answer 1

[Walter Roberson]

Change the line

file_id = fopen('message.txt','r');

to instead refer to the image file that you want to hide, and change

   in=[in dec2bin(file_content(i),7)];

to use 8 instead of 7.

When you are decoding, expect 8 bits per byte instead of 7.

With this change, you can hide any data file that is stored as a sequence of bites, provided that the length is no more than (2^20 - 1), a limit imposed in your line

in = [in dec2bin(file_length,20)]; %character to binary conversion

[Anushka]

Thank you Sir, I did as you have told but now the insertion part works well and the stego image is formed but the extraction part is not working can you please help me . There is no error in the algorithm since it worked well for text data

for dim = 1: 3
    em = im2;
    em = em(:);
    len = length(em);
    in = [];

      in=[in dec2bin(len,30)];

      for i=1:len         %character convert to binary
          in=[in dec2bin(em(i),8)];
      end

      a = im1(:,:,dim);    %get cover image
      [r,c]=size(a);
      final=double(a);
      next=0;
      capacity=0;
   %total no of bits that can be embedded

for x=0:1:r-1 

      for y=0:2:c-1

          enable = 1; %enable=0 when new pixels may fall off the boundary

       p = a(1+x,1+y:2+y); %block of two pixels, pi & pi+1

          p = double(p);

          d = p(1,2) - p(1,1); %d = difference between 2 pixel

          d_abs = abs(d); %absolute difference

          lb=[0 8 16 32 64 128]; %lowerbound

          ub=[7 15 31 63 127 255]; %upperbound

          for i=1:1:6 %test the R boundary

              if((d_abs >= lb(i)) && (d_abs <= ub(i))) %selecting range

                  %check if any pixel in a block fall off the boundary [0,255]

                  even2 = mod(d,2); 

                  m2 = ub(i) - d;

                  if (even2 == 0)

                      Pcheck=[p(1,1)-floor(m2/2) p(1,2)+ceil(m2/2)];

                  else

                      Pcheck=[p(1,1)-ceil(m2/2) p(1,2)+floor(m2/2)];

                  end

                  if(Pcheck(1)<0 || Pcheck(2)<0 || Pcheck(1)>255 || Pcheck(2)>255)

                      enable = 0;

                      break

                  end

                  n = ub(i)-lb(i)+1; %quantization width of range
                  t = floor(log2(n)); %maximum bit can be embedded in 2 pixels
                  capacity=capacity+t; %max capacity of the cover image 

                  %check if next exceeds the length of message
                  if(next>length(in)) 
                      m=0;
                  %check if next+t exceeds the length of message
                  elseif(next+t>length(in)) 
                      if(1+next>=length(in))
                          k=zeros(1,t);
                      else
                          k=in(1+next:length(in));
                      end
                      diff =next+t-length(in);
                      k1=zeros(1,t);
                      if(diff>0)
                          for j=1:next+t-length(in)
                              k1(j)=k(j);
                          end
                      end
                      k=k1;
                      next=next+t;
                      k=bin2dec(char(k));
                      if(1+next>length(in))
                          m=0;
                      else
                          if(d >= 0)
                              dnew = k + lb(i);
                          else
                              dnew = -(k + lb(i));
                          end
                          m = dnew - d;
                      end
                  %if next is less than the length of message
                  else 
                      k=in(1+next:t+next);
                      next=next+t;
                      k=bin2dec(char(k));
                      if(d >= 0)
                          dnew = k + lb(i);
                      else
                          dnew = -(k + lb(i));
                      end
                      m = dnew - d;
                  end

              end
          end

          if (enable == 1)
              even = mod(d,2);
              if (even == 0)
                  P0=[p(1,1)-floor(m/2) p(1,2)+ceil(m/2)];
              else
                  P0=[p(1,1)-ceil(m/2) p(1,2)+floor(m/2)];
              end
              final(1+x,1+y)=P0(1,1);
              final(1+x,2+y)=P0(1,2);
          end

      end
  end
   stego_image(:,:,dim)=final;
  end
    end

[row,col,dim]=size(Image);
% %RecIm=[];
% j=0;
% length=0;

    for p = 1:dim
      layer = Image(:,:,p);
      msg = [];
  flag = 0;
  length=0;
  [row,col,dim]=size(Image);
  j=0;
  finaltxt=[];
  enable = 1;
  % [r1 c1]=size(YourRGBImage);
  % length=r1*c1;
  for x=0:1:row-1
      for y=0:2:col-1
          if (enable == 1) %enable=0 when any pixels may fall off the boundary
              gp = layer(1+x,1+y:2+y); %block of 2 pixels, pi & pi+1
              gp = double(gp);
              d  = gp(1,2) - gp(1,1); %d = difference between 2 pixel
              nd = abs(d); %absolute difference
              lb = [0 8 16 32 64 128]; %lowerbound
              ub = [7 15 31 63 127 255]; %upperbound
              for i=1:1:6 %test the R boundary
                  if(nd>=lb(i)&&nd<=ub(i))
                      %check if any pixel in a block fall off the boundary [0,255]
                      even2 = mod(d,2); 
                      m2 = ub(i) - d;
                      if (even2 == 0)
                          Pcheck=[gp(1,1)-floor(m2/2) gp(1,2)+ceil(m2/2)];
                      else
                          Pcheck=[gp(1,1)-ceil(m2/2) gp(1,2)+floor(m2/2)];
                      end
                      if(Pcheck(1)<0 || Pcheck(2)<0 || Pcheck(1)>255 || Pcheck(2)>255)

                          break
                      end

                      w = ub(i)-lb(i)+1; %quantization width of range
                      t=log2(w); %maximum bit can be embedded between 2 pixel
                      b = nd - lb(i);
                      k=dec2bin(b,t);
                      msg = [msg k];

                      j=j+t;
  % %                     length=length(msg);
  %                     
  %                      
                     if(flag==0 && j>=30)
                        length=bin2dec(msg(1:30))+3; %possible 3 char error 
                        length=length*7;
                        flag=1;
                     end

                    if(flag==1 && j>=length)
                        w1=1;
                        for i=30:7:length-7
                            finaltxt(w1)=bin2dec(msg(1+i:7+i));
                            w1=w1+1;
                          end

   RecIm(:,:,p) = reshape(finaltxt,[8 8]); 

                         enable = 0;
                      end

                  end
              end
          end
  end

end

end
end

[Walter Roberson]

Why are you embedding im2 into all three dimensions of the image? Is that part of the algorithm, to embed the same data three times?

How was im2 created?

Your output seems to be RecIm which is a 3D array whose size is not obvious -- 8 by 8 by something. Which variable holds the extracted data?

[Anushka]

Sir im2 is the secret image of size 8*8 and is color image.I like to embed the RGB secret image into RGB cover image.So I tried to embed the R plane's pixel of the secret image into the R plane of the cover image and similarly for B and G plane pixels.Te extracted data is stored in finaltxt and given to variable RecIm.

[Walter Roberson]

Then shouldn't you be using em = im2(:,:,dim) ?

Note: the Answer I gave above about embedding any kind of file has to do with embedding files, not images. Images are usually encoded into image files for storage on disk -- files that have header information about the image and which might store the image in compressed form. Make sure you know what it is that you are embedding, an image or an image file.

[Anushka]

Sir I am trying to embed an image not an image file.I used em=im2(:,:,dim) still the extraction is not working.

[Walter Roberson]

I am going to sleep now. It might be a number of hours before I look at this.

Sorry but it is 3am here and I am expecting people in the morning.

[Anushka]

Ok Sir.Thank you Sir for your help.Hope you would help me latter.

[PoXiao]

Have you solved the problem of extracting pictures? I also want to know what to do

[aya jaradat]

Have you solved the problem of extracting images?

Please, I am facing the same problem