How do I run the following code

Please ignore the option2 in every menu-driven selection as I need to only include text within an image and then obtain the text back !!!!

The code is :

function [output] = steganography()

%STEGANOGRAPHY: This Function lets a user interactively
%   choose to encode a hidden message within a "canvas image" or decode a
%   hidden message hidden within a "canvas image".
%
% INPUTS: NONE, the user will select them as the program executes.
%
% OUTPUTS:
% - output: Either an Encoded "Canvas Image" or a Decoded Message.

%%David Pipkorn and Preston Weisbrot
% Project: Steganography - Hidden Messages in Images
%

%%STEP 1: Determine Whether User is Encoding or Decoding a Message
enc_dec = input('Welcome to the Steganography Program \nEnter 1 for Encoding, 2 for Decoding:\n');

if enc_dec == 1
    %%STEP A: ENCODING VERSION
    %%STEP 2A: Select "Canvas Image" and "Message File".
    % First Get "Canvas" Image.
    [FileName,PathName] = uigetfile({'*.jpg';'*.png';'*.gif';'*.bmp'},'Select "Canvas Image" to Hide Message.');
    img = imread( strcat(PathName,FileName) );

      % Next get Message File
      msg_type = input('Enter 1 for TEXT Message, 2 for IMAGE Message:\n');
      if msg_type == 1
          [FileName,PathName] = uigetfile('*.txt','Select TEXT MESSAGE.');
          testmsg = fopen( strcat(PathName,FileName) );
          [msg] = fscanf(testmsg,'%c');
      elseif msg_type == 2
          [FileName,PathName] = uigetfile({'*.jpg';'*.png';'*.gif';'*.bmp'},'Select IMAGE MESSAGE.');
          msg = imread( strcat(PathName,FileName) );
      else
          error('Invalid Message Type Selection');
      end

      %%STEP 3A: Prompt User for Encryption Key
      enc_key = input('Please Enter an Encryption Key Between 0 - 255:\n');
      if enc_key < 0 || enc_key > 255
          error('Invalid Key Selection');
      end

      enc_key = uint8(enc_key);

      %%STEP 4A: Allow User to Select SEQUENTIAL or RANDOM Encoding Method
      encode = input('Enter 1 for Sequential Encoding, 2 for Random Encoding:\n');
      if encode == 1
          % SEQUENTIAL ENCODING: This only needs an Encryption Key Input.
          output = stegancoder(img,msg,enc_key);
      elseif encode == 2
          % RANDOM ENCODING: This needs the Encryption Key AND Random Seed
          %   Value.

          % Random Seed Value
          randSeed = input('Please Enter Random Seed Value Between 1 - 100:\n');
          if randSeed < 1 || randSeed > 100
              error('Invalid Random Seed Value')
          end

          randSeed = uint8(randSeed);

          % Final Output
          output = stegancoder_Rand(img,msg,enc_key,randSeed);
      else
          error('Invalid Encoding Selection');
      end

      %%STEP 5A: Write Canvas Image to .BMP File
      % BMP, or bitmap format, was chosen because it DOES NOT use
      %   compression. JPEG compression destroys the message.
      secfn = input('Enter File Name for Image + Message:\n','s');
      nametest = ischar(secfn);
      if nametest == 1
          imwrite(output,strcat(secfn,'.bmp'));
      else
          error('Invalid File Name');
      end

elseif enc_dec == 2
    %%STEP B: DECODING VERSION
    %%STEP 2B: Import "Canvas Image" With Hidden Message.
    [FileName,PathName] = uigetfile('*.bmp','Select "Canvas Image" With Hidden Message.');
    img = imread( strcat(PathName,FileName) );

      %%STEP 3B: Prompt User for Encryption Key
      enc_key = input('Please Enter an Encryption Key Between 0 - 255:\n');
      if enc_key < 0 || enc_key > 255
          error('Invalid Key Selection');
      end

      enc_key = uint8(enc_key);

      %%STEP 4B: Allow User to Select SEQUENTIAL or RANDOM Decoding Method
      decode = input('Enter 1 for Sequential Decoding, 2 for Random Decoding:\n');
      if decode == 1
          % SEQUENTIAL DECODING: This only needs an Encryption Key Input.
          output = stegandecoder(img,enc_key);
      elseif decode == 2
          % RANDOM DECODING: This needs the Encryption Key AND Random Seed
          %   Value.

          % Random Seed Value
          randSeed = input('Please Enter Random Seed Value Between 1 - 100:\n');
          if randSeed < 1 || randSeed > 100
              error('Invalid Random Seed Value')
          end

          randSeed = uint8(randSeed);

          % Final Output
          output = stegandecoder_Rand(img,enc_key,randSeed);
      else
          error('Invalid Encoding Selection');
      end

      %%STEP 5B: Writing Message to .TXT or .JPG File
      secfn = input('Enter File Name for Image + Message:\n','s');
      nametest = ischar(secfn);
      if nametest == 1
          msgtest = ischar(output);
          if msgtest == 1
              % TEXT Message CASE
              fid = fopen(strcat(secfn,'.txt'),'w');
              fwrite(fid,output,'char');
              fclose(fid);
          else
              % IMAGE Message CASE
              imwrite(output,strcat(secfn,'.bmp'));
          end
      else
          error('Invalid File Name');
      end

else
    error('Invalid Selection');
end

function [J] = stegancoder(img,msg,enc_key)
% STEGANCODER: This function "hides" a message within an image that the
%   user provides. The final output is an image file that contains the
%   message protected by encryption and encoding.
% This function will eventually be expanded to randomly "hide" the message
%   across the "canvas" message using the STEGANCODER_RAND Function.
% 
% INPUTS:
% - img: This is the "clean" original image that will be used to hide our
%           secret message.
% - msg: This is the information to be hidden within the original image.
%           This can be a text file or another image file. Image files will
%           be converted to GRAYSCALE IMAGES.
% - enc_key: This is the Encryption Key used for Symmetric XOR Encryption.
%           THIS MUST BE THE SAME FOR SUCCESSFUL DECRYPTION!
%
% OUTPUTS:
% - J: Final image contains the encoded and/or encrypted message

%%David Pipkorn and Preston Weisbrot
% Project: Steganography - Hidden Messages in Images

%%Step 1: Determining Message Type and Normalizing
% The MATLAB Function 'double' is extremely useful for converting both
%   text files into a useful form. If the message is ASCII formatted text, 
%   double will return the integer values for each character. 
% So, 'Hello World' is: 72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100
% For image files we will use 'im2unit8', which forces the pixel values to
%   be represented as integers between 0-255 (just like the text values).

msgtype = ischar(msg);  % If message is text this will be true; 
                        %   false otherwise

if msgtype == 1     % Message = TEXT
    msg_temp = double(msg);     % Converts from ASCII to Integer Values.
    msg_dim = num2str(length(msg_temp));
    msg_length = length(msg_dim);
    z = 0;
    if msg_length < 7
        padtext = 7 - msg_length;
        for z = 1:padtext
            msg_dim = horzcat('0',msg_dim);
        end
        msg_head = horzcat('t',msg_dim);
        % Applying Header To Beginning of Message to be Encoded.
        msg_temp_head = horzcat(msg_head,msg_temp);
    end

else
    % Message = IMAGE
    msg = im2uint8(msg);        % Convert to Integer Value Representation.

      msg_temp = rgb2gray(msg);   % Converts Hidden Message to Grayscale. 
                                  %   Reduces Amount of Data to Hide.

      % Determine Message Image's Size for Encoding in Header                           
      [hideM1,hideN1] = size(msg_temp);
      hideM = num2str(hideM1);
      hideN = num2str(hideN1);
      dimM = length(hideM);
      dimN = length(hideN);
      padM = 0; padN = 0;
      z = 0;

      if dimM < 4
          padM = 4 - dimM;
          for z = 1:padM
              % Zero Padding Dimension if less than 4 Sig Figs.
              hideM = horzcat('0',hideM);
          end
      end
      z = 0;

      if dimN < 4
          padN = 4 - dimN;
          for z = 1:padN
              % Zero Padding Dimension if less than 4 Sig Figs.
              hideN = horzcat('0',hideN);
          end
      end
      msg_head = horzcat(hideM,hideN);
      msg_temp_head = msg_head;

      y = 0;  k = hideM1;
      for y = 1:k
          % Applying Header To Beginning of Message to be Encoded.
          msg_temp_head = horzcat(msg_temp_head,msg_temp(y,:));
      end

end

%%Step 2: Ensuring Sufficient "Hiding Space"
% tot_hiding_pix = max(cumprod(size(img)));
% tot_data = max(cumprod(size(msg_temp_head)));
% 
% if tot_hiding_pix <= tot_data
%     error('Insufficient Hiding Space in Image')
% end

%%Step 3: Encrypting Using XOR Key
% key = 42;  % Used for Test Phase
msg_enc = bitxor(uint8(msg_temp_head),uint8(enc_key));

msg_enc_set = dec2bin(msg_enc, 8);

%%Step 4: Preparing Hiding Canvas
img_prep = im2uint8(img);

%%Step 5: Hiding Data
% I will try to hide the data points using a RGBBGRRG Order. I will be
%   hiding this data along the columns moving from left to right through
%   the target image.
rm = 1; gm = 1; bm = 1;     % Initializing Counters
rn = 1; gn = 1; bn = 1;

[maxM,maxN] = size(img_prep);
z = 0;

% RUN_TIME Variable indicates the number of Message "Words" that need to be
%   encoded in the IMG_PREP "Canvas" Image.
run_time = length(msg_enc_set);

for z = 1:run_time;
    temp_code = msg_enc_set(z,:);
    % Bit 1: Red
    if str2double(temp_code(1)) == 0
        img_prep(rm,rn,1) = bitand(img_prep(rm,rn,1),uint8(254));
    else
        img_prep(rm,rn,1) = bitor(img_prep(rm,rn,1),uint8(1));
    end

      rm = rm + 1;
      % This next step is used to determine whether or not we have reached
      %   the end end of the image. We then need to move to the next column
      %   and reset our pattern to the top row. Since we have no idea when we
      %   will reach this point we have to check this EVERY time after we
      %   increase the rm/gm/bm counter.
      if rm > maxM
          rn = rn + 1;
          rm = 1;
      end
      % Bit 2: Green
      if str2double(temp_code(2)) == 0
          img_prep(gm,gn,2) = bitand(img_prep(gm,gn,2),uint8(254));
      else
          img_prep(gm,gn,2) = bitor(img_prep(gm,gn,2),uint8(1));
      end

      gm = gm + 1;
      if gm > maxM
          gn = gn + 1;
          gm = 1;
      end
      % Bit 3: Blue
      if str2double(temp_code(3)) == 0
          img_prep(bm,bn,3) = bitand(img_prep(bm,bn,3),uint8(254));
      else
          img_prep(bm,bn,3) = bitor(img_prep(bm,bn,3),uint8(1));
      end

      bm = bm + 1;
      if bm > maxM
          bn = bn + 1;
          bm = 1;
      end
      % Bit 4: Blue
      if str2double(temp_code(4)) == 0
          img_prep(bm,bn,3) = bitand(img_prep(bm,bn,3),uint8(254));
      else
          img_prep(bm,bn,3) = bitor(img_prep(bm,bn,3),uint8(1));
      end

      bm = bm + 1;
      if bm > maxM
          bn = bn + 1;
          bm = 1;
      end
      % Bit 5: Green
      if str2double(temp_code(5)) == 0
          img_prep(gm,gn,2) = bitand(img_prep(gm,gn,2),uint8(254));
      else
          img_prep(gm,gn,2) = bitor(img_prep(gm,gn,2),uint8(1));
      end

      gm = gm + 1;
      if gm > maxM
          gn = gn + 1;
          gm = 1;
      end
      % Bit 6: Red
      if str2double(temp_code(6)) == 0
          img_prep(rm,rn,1) = bitand(img_prep(rm,rn,1),uint8(254));
      else
          img_prep(rm,rn,1) = bitor(img_prep(rm,rn,1),uint8(1));
      end
      rm = rm + 1;
      if rm > maxM
          rn = rn + 1;
          rm = 1;
      end
      % Bit 7: Red
      if str2double(temp_code(7)) == 0
          img_prep(rm,rn,1) = bitand(img_prep(rm,rn,1),uint8(254));
      else
          img_prep(rm,rn,1) = bitor(img_prep(rm,rn,1),uint8(1));
      end
      rm = rm + 1;
      if rm > maxM
          rn = rn + 1;
          rm = 1;
      end
      % Bit 8: Green
      if str2double(temp_code(8)) == 0
          img_prep(gm,gn,2) = bitand(img_prep(gm,gn,2),uint8(254));
      else
          img_prep(gm,gn,2) = bitor(img_prep(gm,gn,2),uint8(1));
      end

      gm = gm + 1;
      if gm > maxM
          gn = gn + 1;
          gm = 1;
      end

end

%%Step 6: Final Output
J = img_prep;       % Final Encoding Output
% J = msg_enc_set;  % ENCRYPTION STEP TEST OUTPUT
end

function [msg] = stegandecoder(img,enc_key)
% STEGANDECODER: This function "reveals" hidden messages by reversing the
%   processing steps completed by the STEGANCODER Function.
%
% INPUTS:
% - img: This is image contains a hidden message that needs to be decoded.
% - enc_key: This is the Encryption Key used for Symmetric XOR Decryption.
%           THIS MUST BE THE SAME AS ENCRYPTION STEP FOR SUCCESSFUL 
%           DECRYPTION!
%
% OUTPUTS:
% - msg: This output file will either be a grayscale image or a hidden text
%           message that was encoded into the original image.

%%David Pipkorn and Preston Weisbrot
% Project: Steganography - Hidden Messages in Images

%%Step 1a: Recover Header Set
rm = 1; gm = 1; bm = 1;     % Initializing Counters
rn = 1; gn = 1; bn = 1;

header = [];
[maxM, maxN, chan] = size(img);

for z = 1:8;
    temp = zeros(1,8);
    % Red    
    temp(1,1) = mod(img(rm,rn,1),2);    
    rm = rm + 1;
    % This next step is used to determine whether or not we have reached
    %   the end end of the image. We then need to move to the next column
    %   and reset our pattern to the top row. Since we have no idea when we
    %   will reach this point we have to check this EVERY time after we
    %   increase the rm/gm/bm counter.
    if rm > maxM
        rn = rn + 1;
        rm = 1;
        if rn > maxN
            break
        end
    end
    % Green
    temp(1,2) = mod(img(gm,gn,2),2);
    gm = gm + 1;
    if gm > maxM
        gn = gn + 1;
        gm = 1;
        if gn > maxN
            break
        end
    end
    % Blue
    temp(1,3) = mod(img(bm,bn,3),2);
    bm = bm + 1;
    if bm > maxM
        bn = bn + 1;
        bm = 1;
    end
    % Blue
    temp(1,4) = mod(img(bm,bn,3),2);
    bm = bm + 1;
    if bm > maxM
        bn = bn + 1;
        bm = 1;
    end
    % Green
    temp(1,5) = mod(img(gm,gn,2),2);
    gm = gm + 1;
    if gm > maxM
        gn = gn + 1;
        gm = 1;
        if gn > maxN
            break
        end
    end
    % Red    
    temp(1,6) = mod(img(rm,rn,1),2);    
    rm = rm + 1;
    if rm > maxM
        rn = rn + 1;
        rm = 1;
        if rn > maxN
            break
        end
    end
    % Red    
    temp(1,7) = mod(img(rm,rn,1),2);    
    rm = rm + 1;
    if rm > maxM
        rn = rn + 1;
        rm = 1;
        if rn > maxN
            break
        end
    end
    % Green
    temp(1,8) = mod(img(gm,gn,2),2);
    gm = gm + 1;
    if gm > maxM
        gn = gn + 1;
        gm = 1;
        if gn > maxN
            break
        end
    end      
    tempstr = num2str(temp);
    header = vertcat(header,tempstr);
end

%%Step 1b: Header Analysis - Decrypt and Determine Message Dimensions
% key = 42;  % Used for Test Phase
msg_head_set = bin2dec(header);
temp_head = bitxor(uint8(msg_head_set),uint8(enc_key));

% Case 1: If the Header starts with 't' it is a text file.
% Case 2: If the Header DOESN'T start with 't' then the message is an image
%   with the dimensions described in the header.
if temp_head(1) == 116
    % CASE 1: Text Set
    dim1 = char(temp_head(2:8));
    m = str2double(dim1);
    n = 1;    
else
    % CASE 2: Image Set
    % Determine Dimensions from Header Values
    tempm = char(temp_head(1:4));
    tempn = char(temp_head(5:8));
    m = str2double(tempm');
    n = str2double(tempn');    
end

%%Step 2: Isolate Potential Message
% Recall in Step 5 of the STEGANCODER Function we used a RGBBGRRG Cycle to
%   encode the message set. In this step we need to reverse this process
%   using MODULO arithmatic.

z = 0;

enc_msg = [];
stopmax = (m * n);

for z = 1:stopmax
    temp = zeros(1,8);
    % Red    
    temp(1,1) = mod(img(rm,rn,1),2);    
    rm = rm + 1;
    % This next step is used to determine whether or not we have reached
    %   the end end of the image. We then need to move to the next column
    %   and reset our pattern to the top row. Since we have no idea when we
    %   will reach this point we have to check this EVERY time after we
    %   increase the rm/gm/bm counter.
    if rm > maxM
        rn = rn + 1;
        rm = 1;
        if rn > maxN
            break
        end
    end
    % Green
    temp(1,2) = mod(img(gm,gn,2),2);
    gm = gm + 1;
    if gm > maxM
        gn = gn + 1;
        gm = 1;
        if gn > maxN
            break
        end
    end
    % Blue
    temp(1,3) = mod(img(bm,bn,3),2);
    bm = bm + 1;
    if bm > maxM
        bn = bn + 1;
        bm = 1;
    end
    % Blue
    temp(1,4) = mod(img(bm,bn,3),2);
    bm = bm + 1;
    if bm > maxM
        bn = bn + 1;
        bm = 1;
    end
    % Green
    temp(1,5) = mod(img(gm,gn,2),2);
    gm = gm + 1;
    if gm > maxM
        gn = gn + 1;
        gm = 1;
        if gn > maxN
            break
        end
    end
    % Red    
    temp(1,6) = mod(img(rm,rn,1),2);    
    rm = rm + 1;
    if rm > maxM
        rn = rn + 1;
        rm = 1;
        if rn > maxN
            break
        end
    end
    % Red    
    temp(1,7) = mod(img(rm,rn,1),2);    
    rm = rm + 1;
    if rm > maxM
        rn = rn + 1;
        rm = 1;
        if rn > maxN
            break
        end
    end
    % Green
    temp(1,8) = mod(img(gm,gn,2),2);
    gm = gm + 1;
    if gm > maxM
        gn = gn + 1;
        gm = 1;
        if gn > maxN
            break
        end
    end      
    tempstr = num2str(temp);
    enc_msg = vertcat(enc_msg,tempstr);
end

%%Step 3: Decryption Step
msg_dec_set = bin2dec(enc_msg);
msg_dec = bitxor(uint8(msg_dec_set),uint8(enc_key));
% msg_dec_set = dec2bin(msg_dec,8);

%%Step 4: Message Prep
if temp_head(1) == 116
    % CASE 1: Text Set
    msg_set = msg_dec;
    msg_out = char(msg_set');
else
    % CASE 2: Image Set
    % Determine Dimensions from Header Values
    tempm = char(temp_head(1:4));
    tempn = char(temp_head(5:8));
    m = str2double(tempm');
    n = str2double(tempn');

      % Reshape Message Set into an Image Output
      msg_set = msg_dec;

      count = 1;
      msg_out = uint8(zeros(m,n));
      for y = 1:m
          for x = 1:n
              msg_out(y,x) = msg_set(count);
              count = count + 1;
          end
      end

      msg_out = im2uint8(msg_out);
  %     THIS CODE Never worked for a larger "real" image so we scrapped it.    
  %     msg_img = reshape(msg_set,m,n)';   
  %     msg_out = im2uint8(msg_img);
  end

%%Step 5: Final Output
msg = msg_out;
end

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[Walter Roberson]

What difficulty did you have when you followed the prompts ?