Matlab Program to Watermark/ Extract/ Calc PSNR / Salt Attack (Steganography)

X. Write a Matlab program that received a host image (512x512). Embed an watermark image into host image by using;
i. Embed at 8th bit then check PSNR
ii. Embed at 7th bit then check PSNR
iii. Embed at 6th bit then check PSNR
iv. Embed at 5th bit then check PSNR

Test robustness by using salt and pepper with level 0.01 to 0.09.
Write another program to extract the watermark after the watermarked image has been attacked. Display the all the images produced.

For getting the best result PLEASE TRY ON GRAYSCALE BITMAP IMAGES !!!

Water Marking Program

clc;

bit=input('Please enter which bit you want to use for watermarking? (8 | 7 | 6 | 5)');

[filename1,pathname]=uigetfile('*.*','Please select the cover image');

'www.root25.com developed by Amir

img1=imread(num2str(filename1));

figure(1);

imshow(img1);  

[row,col]=size(img1)

area=row*col;

i=1;

j=1;

k=1;

[filename2,pathname]=uigetfile('*.*','Please select the watermark image');

water_img=imread(num2str(filename2));

[w1,w2] = size(water_img);

imshow(water_img);

wm=dec2bin(water_img);

Wlength=w1*w2*8;  %

host=dec2bin(img1);

cnt=0;

while i < area

        cnt=cnt+1;

        if cnt>Wlength

            break;

        end

        host(i,bit)=wm(j,k);

        k=k+1;

        if k>8

            k=1;

            j=j+1;

        end

       i=i+1;

 end

   key1=w1

   key2=w2

  

final=bin2dec(host);

final=reshape(final,row,col);

img1(1:row,1:col)=final(1:row,1:col);

output_filename=[num2str(bit), 'th_bit_watermarked.bmp'];

imwrite(img1,output_filename); 

imshow(img1);

PSNR Calculator Program

clc;

[filename1,pathname]=uigetfile('*.*','Please select the original image');

'www.root25.com developed by Amir

original=imread(num2str(filename1));

[filename2,pathname]=uigetfile('*.*','Please select the watermarked image');

watermarked=imread(num2str(filename2));

figure(1);

imshow(original);

figure(2);

imshow(watermarked);    

[row,col] = size(original)

size_host = row*col;

 o_double = double(original);

 w_double = double(watermarked);

 s=0;

 for j = 1:size_host;

 s = s+(w_double(j) - o_double(j))^2 ;

 end

 vr=s/size_host;

 psnr =10*log10((255)^2/vr);

 display 'The PSNR is :',psnr

Salt & Pepper Attack Program

clc;

[filename1,pathname]=uigetfile('*.*','Please select the watermarked image');

'www.root25.com developed by Amir

watermarked=imread(num2str(filename1));

Attack_watermarked=imnoise(watermarked,'salt & pepper',0.09);

% this number will change between 0.01 to 0.09

imwrite(Attack_watermarked,strcat('salt_09_',filename1));

Extraction Program

clc;

bit=input('Please define whic bit you want to extract from? (8 | 7 | 6 | 5)');

[filename1,pathname]=uigetfile('*.*','select the image');

img1=imread(num2str(filename1));

imshow(img1);

'www.root25.com developed by Amir

[row,col]=size(img1);

Hlength=row*col;

i=1;

j=1;

k=1;

row=150; % our embed row

col=150; % our embed col

wmimage=imread('like.bmp');

wmimage=imresize(wmimage,[row col]);

wm=dec2bin(wmimage);

Wlength=row*col*8;

host=dec2bin(img1);

cnt=0;

while i <= Hlength

        cnt=cnt+1;

        if cnt>Wlength

            break;

        end

        wm(j,k)=host(i,bit);

        k=k+1;

        if k>8

            k=1;

            j=j+1;

        end

       i=i+1;

end

    

wm1=bin2dec(wm);

wm2=reshape(wm1,row,col);

wmimage(1:row,1:col)=wm2(1:row,1:col);

output_filename=['extract_', filename1];

imwrite(wmimage,output_filename);

imshow(wmimage);

Watermarking Result

Extraction Result

We can conclude from the result of the watermark that the best result is when we try to embed using the 8th bit , least significant bit (LSB) and when we used the 5th bit we got the worse result and clearly we can see by eyes that something is wrong with image.