I require a code for embedding and extraction of a watermark from an image (DCT Domain). Please help.

we want to - embed a watermark - extract d watermark - prevent it from attacks - provide additional functionalities like security, robustness ...

[Walter Roberson]

What have you done in your assignment?

[Lester]

This code is how far we could go.....it is for embedding of a watermark on an image....we want the code for extraction on similar lines-->

clc, clear all I = imread('C:\Users\pereira\Desktop\t1.jpg'); watermark = imread('C:\Users\pereira\Desktop\event.jpg'); % Scale watermark if needed % I scaled mine to 1/5 its original size watermark = imresize(watermark , 0.2); % Replace pixels at bottom right %val = (size(I,1)-size(watermark,1) + 1); %disp(val);

I((size(I,1)-size(watermark,1) + 1):end,( size( I, 2)-size( watermark, 2) + 1):end, 1:end) = watermark; imshow(I)

[Lester]

Our main aim is using dct algorithms

[Walter Roberson]

That code is unlikely to work. '%' marks a comment that extends to the end of the line, and you only have two lines of code.

[Lester]

Okayy so we've done some more work and research and this is we could get..please rectify the below sir..

clear all; close all; clc;
image1=imread('C:\Documents and Settings\comps\My Documents\My Pictures\Blue1.jpg');
imshow(image1); title('Original image');% orginal image for watermarking
[ori_row,ori_col]=size(image1)
host_length=ori_row*ori_col;

i=1;
j=1;
k=1;

wmimage=imread('C:\Documents and Settings\comps\My Documents\My Pictures\watermark3.jpg');
[wm_row,wm_col] = size(wmimage);
imshow(wmimage); title('Watermark image');

wm=dec2bin(wmimage);
wm_length=wm_row*wm_col*8;

host=dec2bin(image1);

counter=0; 

while i < host_length

          counter=counter+1;

          if counter > wm_length
              break;
          end

          host(i,8)=wm(j,k);
          k=k+1;

          if k>8
              k=1;
              j=j+1;
          end

          i=i+1;
  end

      key1=wm_row
      key2=wm_col

im1=bin2dec(host);
im1=reshape(im1,ori_row,ori_col);
image1(1:ori_row,1:ori_col)=im1(1:ori_row,1:ori_col);

display 'After embed';

imwrite(image1,'wmarked.bmp'); % saves the watermarked image as a bmp file
imshow(image1);title('Watermarked image');

[Walter Roberson]

What difficulty are you encountering with that code?

[as825]

Can anyone tell how to extract the watermark that is embedded with the help of above code?

[Deepa lakshmi]

sir i need to hide a entire file in a image by using LSB in steganography, not watermarking please help me sir

Answer 1

[Image Analyst]

There is a huge body of work way ahead of you in that field. Please review what has been done before here: http://iris.usc.edu/Vision-Notes/bibliography/contentschar.html#OCR,%20Document%20Analysis%20and%20Character%20Recognition%20Systems:

23.3 Watermarks, Watermarking

      23.3.1 Watermarks, Survey, Comparisons, Evaluations
      23.3.2 Watermark Techniques
      23.3.3 Watermark Techniques Based on Human Visual System, Perceptual Models
      23.3.4 Spread Spectrum Watermarks
      23.3.5 Watermarks in Transform Domains, Compressed Images
      23.3.6 Adaptive Watermark Techniques
      23.3.7 Wavelets for Watermarks
      23.3.8 Image Hiding, Data Hiding, Steganography, Steganalysis
          23.3.8.1 Data Hiding, Steganography, LSB, Least Significant Bit
          23.3.8.2 Halftone Images, Compressed Images: Image Hiding, Data Hiding, Steganography
          23.3.8.3 Surveys, Image Hiding, Data Hiding, Steganography 
      23.3.9 Watermarks for Copyright, Ownership Protection, Authentication, Verification, Forgery
          23.3.9.1 Tamper Detection
          23.3.9.2 Fragile Watermarks
          23.3.9.3 Encryption, Visual Cryptography, Authentication 
      23.3.10 Watermarks: Extraction, Detection or Recovery
      23.3.11 Watermarks in Video and Multi-Media, Other Data
          23.3.11.1 Video Data Hiding, Data Hiding in Video, Video Steganography

For what it's worth, here's my watermarking code. It uses the concepts you want to use.

% Demo to watermark an image by hiding another image in a certain bit
% plane.  Sometimes called "LSB Watermarking" or something similar.
% User is asked which bit plane they want to hide the image in.

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.
fontSize = 12;

% Read in the image what will have another image hidden into it.
baseFileName='moon.tif';
% baseFileName='cameraman.tif';
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
  % Didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
originalImage = imread(fullFileName);

% Get the number of rows and columns in the original image.
[visibleRows visibleColumns numberOfColorChannels] = size(originalImage);
if numberOfColorChannels > 1
  % If it's color, extract the red channel.
  originalImage = originalImage(:,:,1);
end

% Display the original gray scale image.
subplot(3, 3, 4);
imshow(originalImage, []);
title('Original Grayscale Starting Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 

% read the message image you want to hide in the cover image
baseFileName='cameraman.tif';
% baseFileName='moon.tif';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
  % Didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
hiddenImage = imread(fullFileName);
% Get the number of rows and columns in the hidden image.
[hiddenRows hiddenColumns numberOfColorChannels] = size(hiddenImage);
if numberOfColorChannels > 1
  % If it's color, extract the red channel.
  hiddenImage = hiddenImage(:,:,1);
end
% Display the image.
subplot(3, 3, 1);
imshow(hiddenImage, []);
title('Image to be Hidden', 'FontSize', fontSize);

% Let's compute and display the histogram.
[pixelCount grayLevels] = imhist(hiddenImage);
subplot(3, 3, 2); 
bar(pixelCount);
title('Histogram of image to be hidden', 'FontSize', fontSize);
xlim([0 grayLevels(end)]); % Scale x axis manually.
grid on;

thresholdValue = 70;
binaryImage = hiddenImage < thresholdValue;
% Display the image.
subplot(3, 3, 3);
imshow(binaryImage, []);
caption = sprintf('Hidden Image Thresholded at %d', thresholdValue);
title(caption, 'FontSize', fontSize);

% Get the bit plane to hide the image in.
prompt = 'Enter the bit plane you want to hide the image in (1 - 8) ';
dialogTitle = 'Enter Bit Plane to Replace';
numberOfLines = 1;
defaultResponse = {'6'};
bitToSet = str2double(cell2mat(inputdlg(prompt, dialogTitle, numberOfLines, defaultResponse)));

% If image to be hidden is bigger than the original image, scale it down.
if hiddenRows > visibleRows || hiddenColumns > visibleColumns
  amountToShrink = min([visibleRows / hiddenRows, visibleColumns / hiddenColumns]);
  binaryImage = imresize(binaryImage, amountToShrink);
  % Need to update the number of rows and columns.
  [hiddenRows hiddenColumns] = size(binaryImage);
end

% Tile the hiddenImage, if it's smaller, so that it will cover the original image.
if hiddenRows < visibleRows || hiddenColumns < visibleColumns
  watermark = zeros(size(originalImage), 'uint8');
  for column = 1:visibleColumns
    for row = 1:visibleRows
      watermark(row, column) = binaryImage(mod(row,hiddenRows)+1, mod(column,hiddenColumns)+1);
    end
  end
  % Crop it to the same size as the original image.
  watermark = watermark(1:visibleRows, 1:visibleColumns);
else
  % Watermark is the same size as the original image.
  watermark = binaryImage;
end
% Display the thresholded binary image - the watermark alone.
subplot(3, 3, 5);
imshow(watermark, []);
caption = sprintf('Hidden Image\nto be Inserted into Bit Plane %d', bitToSet);
title(caption, 'FontSize', fontSize);

% Set the bit of originalImage(a copy, actually) to the value of the watermark.
watermarkedImage = originalImage; % Initialize
for column = 1 : visibleColumns
  for row = 1 : visibleRows
    watermarkedImage(row, column) = bitset(originalImage(row, column), bitToSet, watermark(row, column));
  end
end

% Display the image.
subplot(3, 3, 6);
imshow(watermarkedImage, []);
caption = sprintf('Final Watermarked Image\nwithout added Noise');
title(caption, 'FontSize', fontSize);

% add noise to watermarked image
noisyWatermarkedImage = imnoise(watermarkedImage,'gaussian', 0, 0.0005);

% Display the image.
subplot(3, 3, 7);
imshow(noisyWatermarkedImage, []);
caption = sprintf('Watermarked Image\nwith added Noise');
title(caption, 'FontSize', fontSize);

%====================================================================================
% Now let's pretend we are starting with the watermarked noisy corrupted image.
% We want to recover the watermark.

% Use the known bitplane of watermarked image to recover the watermark.
recoveredWatermark = zeros(size(noisyWatermarkedImage));
recoveredNoisyWatermark = zeros(size(noisyWatermarkedImage));
for column = 1:visibleColumns
  for row = 1:visibleRows
    recoveredWatermark(row, column) = bitget(watermarkedImage(row, column), bitToSet);
    recoveredNoisyWatermark(row, column) = bitget(noisyWatermarkedImage(row, column), bitToSet);
  end
end

% Scale the recovered watermark to 0=255
recoveredWatermark = uint8(255 * recoveredWatermark);
recoveredNoisyWatermark = uint8(255 * recoveredNoisyWatermark);

% Display the images.
subplot(3, 3, 8);
imshow(recoveredWatermark, []);
caption = sprintf('Watermark Recovered\nfrom Bit Plane %d of\nNoise-Free Watermarked Image', bitToSet);
title(caption, 'FontSize', fontSize);
% Display the images.
subplot(3, 3, 9);
imshow(recoveredNoisyWatermark, []);
caption = sprintf('Watermark Recovered\nfrom Bit Plane %d of\nNoisy Watermarked Image', bitToSet);
title(caption, 'FontSize', fontSize);
msgbox('Done with demo!');

[Lester]

Thank you sir. Very grateful.

[Nisder Fiza]

hello sir is that code for embed watermark to an image

[Image Analyst]

Like the comments say, it embeds a hidden (or not so hidden depending on what bit plane you choose to encode it into) watermark. Then it recovers the watermark from the combined image.

[lolo bobo]

sir can you please tell 1 embedding and extraction algorithm using dct, dwt. i shall be very helpful

[Walter Roberson]

Image Analyst posted an entire bibliography of those algorithms. Do you need us to go into Google Scholar and pick one algorithm out at random for you? Because that's how you get Orcs.

[afaf jaw]

Image Analyst

I require a code for embedding and extraction of a steganography from an image (DCT Domain). Please help

[Image Analyst]

It's not my field. All I have is the simple demo I posted. I don't have any other code to give you. If you need more help, click This Link and they will gladly write the code you need, if you want.

Answer 2

[Lester]

Very grateful sir...but the code you have provided is LSB watermarking..what about the code in the DCT domain? is it the same?

[Image Analyst]

Probably not. Watermarking is not my field so I don't know much about that field.

[Lester]

okayy thanks anyways sir

Answer 3

[diksha]

plz tell me latest project in watermarking which i can make ? & help me for that coding so that i can easily understand & make matlab project.