compusoft, 1(1),1-7

1Volume-I, Issue-I (2012)

Implementation of Digital Watermarking Using MATLAB Software

Karnpriya Vyas 1, Kirti Sethiya2, Sonu Jain 3

1 Dept. of Electronics & communication, RGPV2 Dept. of Computer Engineering, GTU

3 Dept. of Computer science & Engineering, RGPV

[email protected], [email protected], [email protected]

Abstract: Digital watermarking holds significant promise as one of the keys to protecting proprietary digital content in the coming years. It focuses on embedding information inside a digital object such that the embedded information is in separable bound to the object. The proposed scheme has been implemented on MATLAB, as it is a high level technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numerical computation. We wanted to know about how one can embed information in an image such that he can later claim the ownership of that image by extracting back the embedded information. Hence, copyright protection of images was our main motivation in starting this project. This paper includes, Implementation of several watermarking algorithms and examines them in terms of how they meet the requirements of different applications and general requirements of watermarking.

Keywords: MATLAB, Algorithms, Digital watermarking, Security

I. INTRODUCTION

The advent of the Internet and the wide availability of computers and printers make digital data exchange and transmission a simple task. However, making digital data accessible to others through networks also creates opportunities for malicious parties to make salable copies of copyrighted content without permission of the content owner.

A digital watermark is an invisible signature embedded inside an image to show authenticity and ownership. An effective digital watermark should be perceptually invisibleto prevent obstruction of the original image. It should be statistically invisible to prevent detection, and it should also be robust to many image manipulations, such as filtering, additive noise, and compression. Digital Watermarking is the process of embedding information into digital multimedia content such that the information (which we call the watermark) can later be extracted or detected for a variety of purposes including copy prevention and control. Digital watermarking has been proposed as a new, alternative method to enforce the intellectual property rights and protect digital media from tampering. It involves

a process of embedding into a host signal a perceptually transparent digital signature, carrying a message about the

Signature is called the digital watermark. The digital watermark contains data that can be used in various applications, including digital rights management, broadcast monitoring and tamper proofing. Although perceptually transparent, the existence of the watermark is indicated when watermarked media is passed through an appropriate watermark detector. Figure 1.1 gives an overview of the general watermarking system. A watermark, which usually consists of a binary data sequence, is inserted into the host signal in the watermark embedder. Thus, a watermark embedder has two inputs; one is the watermark message (usually accompanied by a secret key) and the other is the host signal (e.g. image, video clip, audio sequence etc.). The output of the watermark embedder is the watermarked signal, which cannot be perceptually discriminated from the host signal. The watermarked signal is then usually recorded or broadcasted and later presented to the watermark detector. The detector determines whether the watermark is present in the tested multimedia signal, and if so, what

COMPUSOFT, An international journal of advanced computer technology, 1 (1), 2012 2012, COMPUSOFT All Rights Reserved

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message is encoded in it. The research area of watermarking is closely related to the fields of information hiding and steganography. The three fields have a considerable overlap and many common technical solutions. However, there are some fundamentalphilosophical differences that influence the requirements and therefore the design of a particular technical solution. Information hiding (or data hiding) is a more general area, encompassing a wider range of problems than the watermarking. The term hiding refers to the process of making the information imperceptible or keeping the existence of the information secret. Steganography is a word derived from the ancient Greek words steganos , which means covered and graphia, which in turn means writing. It is an art of concealed communication. Therefore, we can define watermarking systems as systems in which the hidden message is related to the host signal and non-watermarking systems in which the message is unrelated to the host signal.

Host Signal

Watermarked Signal Detected Messege

Watermark Message

Digital watermarking has become an active and important area of research, and development and commercialization of watermarking techniques is being deemed essential to help address some of the challenges faced by the rapid proliferation of digital content.

II. DESIGNING AND IMPLEMENTATION

2.1 ALGORITHM FOR COLORED IMAGES: We used the middle band coefficient exchange algorithm as basis for embedding and recovery of the watermark from colored images.

2.2 EMBEDDING ALGORTIHM: The watermark is embedded separately in all color channels. A block of 8*8 is considered and frequency transformation (DCT) of each block is done. For-loop for length of the watermark

DCT for each block:For red: p=dct2(image(j:j+blocksize-1,i:i+blocksize-1,1));For green: p=dct2(image(j:j+blocksize-1,i:i+blocksize-1,2));For blue: p=dct2(image(j:j+blocksize-1,i:i+blocksize-1,3));

Each bit of the monochromatic watermark represents embedding in each block as shown below if 0 is encountered if

p(1,2)>p(2,1)

III. SOURCE CODE

Step 1:- Introduction window for watermarking. (Fig. 3.1)

Fig. 3.1 Fig. 3.2

function pushbutton1_Callback (hObject, eventdata, handles)

close main;

selectimage;

Step 2:- Selection of image and convert image rgb to gray. (Fig. 3.2)

function pushbutton2_Callback(hObject, eventdata, handles)

close selectimage;

rgbgray;


global img1;

[ans,pathname]=uigetfile(...%opens folder to select input image

{'*.jpg';'*.jpeg'...

}, ...

'Select an IMAGE');

I=[pathname ans];

img1=imread([pathname ans]);

Water marker Embedder

Watermarker Detector


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img1=imresize(img1,[160 160]);

imshow(img1)


global img1;

clc

preview(vid) ;

pause

img=getsnapshot(vid); % acquiring of image from camera

Fig. 3.3

closepreview

delete(vid);

img1=imresize(img,[320 240]); % size normalization

k=img1;

imshow(img1)

Step 3:- Convert image from gray scale to black and white.

function graybw_OpeningFcn(hObject, eventdata, handles, varargin)

global BW;

global I;

BW=im2bw(I);

imshow(BW)

Fig. 3.4 Fig. 3.5


close graybw;

finfface

Step 4:- Crop image and provide binary co-ordinates.


close finfface;

cropimage;

Step 5:- Show cropped image watermarking image to watermark with another.


close cropimage;

step1;

Fig. 3.6 Fig. 3.7

function pushbutton1_Callback(hObject,eventdata,handles)

close step1;


global img1;

[ans,pathname]=uigetfile( ...%opens folder to select input image

{'*.jpg';'*.png';...

}, ...

'Select an IMAGE');

I=[pathname ans];



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imshow(img1)

Step 7: Selection to send either image or text.

function step3_OpeningFcn(hObject, eventdata, handles, varargin)

global img1;

imshow(img1)

global ext_out

ext_out='bmp';

functionpushbutton1_Callback(hObject,eventdata, handles)

close step3;

step5;

functionpopupmenu1_Callback(hObject,eventdata, handles)

val = get(hObject,'Value');

str = get(hObject, 'String');

global img1;global img;global imgw;global ext_out;global I1;

ext_out='bmp';

switch str{val}

case 'TEXT'

case 'IMAGE'

watermark=I1;

[imgw]=watermark_img(img1,watermark) ;

imwrite(imgw,['watar_image' '.' ext_out],ext_out);

end

Fig. 3.8 Fig. 3.9

Step 8:- Watermarked image and provide link to upload image. (Fig. 3.9)


close step5;

web http://wikisend.com/

IV. SOURCE CODE FOR DEWATER MARKING

Step1:-Introduction window for de-watermarking.(Fig. 4.1)

Function pushbutton1_Callback(hObject, eventdata, handles)

close main;

step1;

Fig. 4.1 Fig. 4.2

Step 2:- Image selection (Fig. 4.2)


global img1;

[ans,pathname]=uigetfile( ...

{'*.bmp';... }, ... 'Select an IMAGE');

I=[pathname ans];


imshow(img1


close step1;

step3;

Step 3:- Extracting process. (Fig. 4.3)

function step3_OpeningFcn(hObject, eventdata, handles, varargin)


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global img1

axes(handles.axes1)

imshow (img1)


close step3;

step4;

function popupmenu1_Callback(hObject, eventdata, handles)

val = get(hObject,'Value');

str = get(hObject, 'String');

global img1;global img;global imgw;global ext_out;global I1;

switch str{val};

case 'TEXT'

st=dewatermark_k(img1);

set(handles.edit1,'visible','on')

set(handles.text2,'visible','on')

set(handles.edit1,'String',st)

case 'IMAGE'

img_logo=dewatermark_img(img1);

set(handles.axes2,'visible','on')

set(handles.text3,'visible','on')

axes(handles.axes2)

imshow(img_logo)

imwrite(img_logo,'hidden.jpg')

end

Fig. 4.3

Step 4:- Dewatermarked image.


Fig. 4.4

V. PROCESS STEPS FOR WATERMARKING

Step 1:- Introduction window opens for watermarking.

Fig. 5.1 Fig. 5.2

Step 2:- selection window opens and ask for select image source. It has two options either from folder or camera. If we select folder then open the folder of computer to select the image. In second option Camera we can capture image at a time from the web camera.

Step 3:- In this step next window opens which provide gray scale image of original image. In this stage image converts from 3D to 2D image.

Step 4:- In this step next window opens and convert grayscale image to black & white image.


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Fig. 5.3 Fig. 5.4

Step 5:- Find face in gray scale image and after cropping located the area for crop.

Fig. 5.5

Step 6:- In this step window shows the finally cropped image.

Fig. 5.6

Step 7:- Provide next window to select another image from the folder to watermark.

Fig. 5.7

Step: 8- Provide selection either for image or text to watermark, and then watermarked both the images. Embedded cropped image in to the image selected from folder.

Fig. 5.8

VI. PROCESS STEPS FOR DEWATER MARKING

Step 1:- Introduction window opens for dewatermarking.

Fig. 6.1

Step 2:-Provide next window to select another image from the folder to watermark.

Fig. 6.2


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Step 3:- Provide next window to select another image from the folder to watermark.

Fig. 6.3

Step 4:- final dewater marked image.

Fig. 6.4

VII. CONCLUSION

Digital watermarking holds significant promise as one of the keys to protecting proprietary digital content in the coming years. It focuses on embedding information inside a digital object such that the embedded information is in separable bound to the object. Tampering with the watermark or otherwise altering a watermarked object should always be detectable, and attempting to remove a watermark from its object should cause to be that object useless. Currently, watermarking suffers from several drawbacks that prevent it from providing the creators of digital content with a solid guarantee of copyright protection.

The watermarking research is progressing very fast and numerous researchers from various fields are focusing to develop some workable scheme. Different companies also working to get commercial products. We hope some commercial and effective schemes will be available in future.

VIII. REFERENCES

[1] Wang, Y., Alan Pearmain., 2004. Blind image data hiding based on self reference. Pattern Recognition Letters 25, pp. 1681-1689.

[2] Barni, M., Bartolini, M., Piva, F.V., 2001. Improved wavelet based watermarking through pixel-wise masking. IEEE Transactions on Image Processing 10, pp. 783-791.

[3] Lee, C., Lee, H., 2005. Geometric attack resistant watermarking in wavelet transforms domain, Optics Express vol.13, no.4, and pp.1307-1321.

[4] Chandra Mohan B, Srinivas Kumar S, Chatterjee B.N., 2006. Digital Image watermarking in dual domains at IET Visual Information Engineering, VIE 2006 at Leela Palace, Bangalore, 26-28th September 2006.

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