% Distortionless data hiding based on integer wavelet transform (Watermark Embedding)
% Guorong Xuan Jiang Zhu Jidong Chen Shi, Y.Q. Zhicheng Ni Wei Su
% Department of Computer Science, Tongji University, Shanghai
%
% This paper appears in: Electronics Letters
% Publication Date: 5 Dec 2002
% Volume: 38, Issue: 25
% On page(s): 1646- 1648
% ISSN: 0013-5194
% August 12, 2007, 4:37pm
% updated August 19, 2007, 5:45pm
% updated 13 December, 2008
% By: Asad (asad_82@yahoo.com)
% NOTE: In case of error change the bit plane number as embedding may not be possible using that bitplane.
% Also in order to achieve more bpp, bit plane number can be changed.
clear all;
close all;
% define constants
BITPLANE_NUMBER = 4; %4 % specifies the bitplane number to embedd watermark
ERROR_NUM = 16; %16 % prevents this gray value from being used in embedding
WM_SIZE = 300;
% select the bitplane number and then the corresponding error num from the
% table below
% BITPLANE_NUMBER = [1 2 3 4 5 6 7 8]
% ERROR_NUM = [128 64 32 16 8 4 2 1]
disp('------------------------ Embedding -------------------------------');
% read image and convert to gray scale if necessary
originalImage = imresize(imread('lena.tif'),[512 512],'bicubic');
if (isrgb(originalImage))
originalImage = rgb2gray(originalImage);
end
% STEP 1: perform necessary preprocessing
%[valCount,X] = imhist(originalImage);
% STEP 2: perfom wavelet decomposition
LS = liftwave('cdf2.2','Int2Int');
[CA,CH,CV,CD] = lwt2(double(originalImage),LS);
% STEP 3: construct binary images from 5th bit of CH, CV and CD
for i=1:size(CH,1)
for j=1:size(CH,2)
% for constructing binary image using CH
binSeq = dec2bin(abs(CH(i,j)),8);
if binSeq(BITPLANE_NUMBER) == '1'
bICH5(i,j) = 2;
else
bICH5(i,j) = 1;
end
% for constructing binary image using CV
binSeq = dec2bin(abs(CV(i,j)),8);
if binSeq(BITPLANE_NUMBER) == '1'
bICV5(i,j) = 2;
else
bICV5(i,j) = 1;
end
% for constructing binary image using CD
binSeq = dec2bin(abs(CD(i,j)),8);
if binSeq(BITPLANE_NUMBER) == '1'
bICD5(i,j) = 2;
else
bICD5(i,j) = 1;
end
end
end
% STEP 4a: Compress data in 5th Bit plane of CH
% find how many times 1 occurs in the level 5 binary bICH5 (horizontal)
[xx,yy,val] = find(bICH5 == 1);
totalVals = size(CH,1)*size(CH,2);
% code the sequence using arithmetic coding
count1 = [round((size(xx,1)/totalVals)*100) round(((totalVals - size(xx,1))/totalVals) * 100)];
seq1 = reshape(bICH5,1,size(CH,1)*size(CH,2));
arcCH5 = arithenco(seq1,count1);
str = sprintf('Original CH Bits Length = %d ------ Compressed CH Bits Length = %d',size(seq1,2),size(arcCH5,2));
disp(str);
% STEP 4b: Compress data in 5th Bit plane of CV
% find how many times 1 occurs in the level 5 binary bICV5 (vertical)
[xx,yy,val] = find(bICV5 == 1);
totalVals = size(CV,1)*size(CV,2);
% code the sequence using arithmetic coding
count2 = [round((size(xx,1)/totalVals)*100) round(((totalVals - size(xx,1))/totalVals) * 100)];
seq2 = reshape(bICV5,1,size(CV,1)*size(CV,2));
arcCV5 = arithenco(seq2,count2);
str = sprintf('Original CV Bits Length = %d ------ Compressed CV Bits Length = %d',size(seq2,2),size(arcCV5,2));
disp(str);
% STEP 4c: Compress data in 5th Bit plane of CD
% find how many times 1 occurs in the level 5 binary bICD5 (diagonal)
[xx,yy,val] = find(bICD5 == 1);
totalVals = size(CD,1)*size(CD,2);
% code the sequence using arithmetic coding
count3 = [round((size(xx,1)/totalVals)*100) round(((totalVals - size(xx,1))/totalVals) * 100)];
seq3 = reshape(bICD5,1,size(CD,1)*size(CD,2));
arcCD5 = arithenco(seq3,count3);
str = sprintf('Original CD Bits Length = %d ------ Compressed CD Bits Length = %d',size(seq3,2),size(arcCD5,2));
disp(str);
% STEP 5: read the watermark and reshape it for insertion
watermark = imresize(rgb2gray(imread('logo_im.jpg')),[WM_SIZE WM_SIZE],'bicubic');
%watermark = imresize(DMlcd5,[WM_SIZE WM_SIZE],'bicubic');
watermark = im2bw(watermark);
%figure,imshow(watermark,[]),title('Watermark');
watermark = reshape(watermark,1,WM_SIZE*WM_SIZE);
% STEP 6: Insert the watermark and compressed data into the image
% compute length of data to insert
dataLength = size(watermark,2) + size(arcCH5,2) + size(arcCV5,2) + size(arcCD5,2) + 6*8 + 4*16;%(2*8)*3;
available = size(CH,1)*size(CH,2) + size(CV,1)*size(CV,2) + size(CD,1)*size(CD,2);
if available < dataLength
disp('Data to Embedd must be less than available limit.');
end
% allocate memory and initialize
embedData = zeros(1,dataLength);
% insert the header information
str1 = dec2bin(count1(1,1),8); str2 = dec2bin(count1(1,2),8);
header = strcat(str1,str2);
str1 = dec2bin(count2(1,1),8); str2 = dec2bin(count2(1,2),8);
header = strcat(header,str1,str2);
str1 = dec2bin(count3(1,1),8); str2 = dec2bin(count3(1,2),8);
header = strcat(header,str1,str2);
% insert length of each sequence for decoding
str1 = dec2bin(size(arcCH5,2),16); str2 = dec2bin(size(arcCV5,2),16);
str3 = dec2bin(size(arcCD5,2),16); str4 = dec2bin(size(watermark,2),32);
header = strcat(header,str1,str2,str3,str4);
for i=1:size(header,2)
if header(1,i) == '1'
embedData(1,i) = 1;
else
embedData(1,i) = 0;
end
end
% get the header length
HL = size(header,2);
% concatenate data to get a single compressed data vector
embedData(1,HL+1:HL+size(arcCH5,2)) = arcCH5(1,:);
embedData(1,HL+size(arcCH5,2)+1:(HL+size(arcCH5,2) + size(arcCV5,2))) = arcCV5(1,:);
embedData(1,HL+size(arcCH5,2)+ size(arcCV5,2)+1:(HL + size(arcCH5,2) + size(arcCV5,2) + size(arcCD5,2))) = arcCD5(1,:);
embedData(1,HL+size(arcCH5,2)+ size(arcCV5,2)+size(arcCD5,2)+1:(HL+size(arcCH5,2) + size(arcCV5,2) + size(arcCD5,2)+ size(watermark,2))) = watermark(1,:);
originalBitsLength = HL + size(arcCH5,2)+ size(arcCV5,2)+size(arcCD5,2);
% embedd compressed data, watermark and header information
index = 1; % counter for obtaining 8 bit chunks
brk = 0;
for x=1:size(CH,1)
for y=1:size(CH,2)
if CH(x,y) ~= -ERROR_NUM
neg = 0;
if CH(x,y) < 0
neg = 1;
end
binSeq = dec2bin(abs(CH(x,y)),8);
if embedData(1,index) == 1
binSeq(BITPLANE_NUMBER) = '1';
else
binSeq(BITPLANE_NUMBER) = '0';
end
num = bin2dec(binSeq);
if neg == 1
CH(x,y) = num * -1;
else
CH(x,y) = num;
end
% break the loop if all watermark bits are embedded
if index < size(embedData,2)
index = index + 1;
else
brk = 1; break;
end
end
end
if brk == 1
break;
end
end
if index < size(embedData,2)
for x=1:size(CV,1)
for y=1:size(CV,2)
if CV(x,y) ~= -ERROR_NUM
neg = 0;
if CV(x,y) < 0
neg = 1;
end
binSeq = dec2bin(abs(CV(x,y)),8);
if embedData(1,index) == 1
binSeq(BITPLANE_NUMBER) = '1';
else
binSeq(BITPLANE_NUMBER) = '0';
end
num = bin2dec(binSeq);
if neg == 1
CV(x,y) = num * -1;
else
CV(x,y) = num;
end
% break the loop if all watermark bits are embedded
if index < size(embedData,2)
index = index + 1;
else
brk = 1; break;
end
end
end
if brk == 1
break;
end
end
end
if index < size(embedData,2)
for x=1:size(CD,1)
for y=1:size(CD,2)
if CD(x,y) ~= -ERROR_NUM
neg = 0;
if CD(x,y) < 0
neg = 1;
end
binSeq = dec2bin(abs(CD(x,y)),8);
if embedData(1,index) == 1
binSeq(BITPLANE_NUMBER) = '1';
else
binSeq(BITPLANE_NUMBER) = '0';
end
num = bin2dec(binSeq);
if neg == 1
CD(x,y) = num * -1;
else
CD(x,y) = num;
end
% break the loop if all watermark bits are embedded
if index < size(embedData,2)
index = index + 1;
else
brk = 1; break;
end
end
end
if brk == 1
break;
end
end
end
% compute inverse integer wavelet transform
watermarkedImage = ilwt2(CA,CH,CV,CD,LS);
% [tx,ty,tval] = find(watermarkedImage > 256);
% if ~isempty(tx)
% disp('Watermarked Image values greater than 256');
% end
% [tx,ty,tval] = find(watermarkedImage <= 0);
% if ~isempty(tx)
% disp('Watermarked Image values less than equal to 0');
% end
imwrite(uint8(watermarkedImage),'Watermarked Image.bmp','bmp');
str = sprintf('Payload(bpp) = %f -- Embedded Data(Header+Original Bits+Watermark) = %d bits -- Watermark Length = %d bits',(dataLength-originalBitsLength)/(4*(size(CH,1)*size(CH,1))),dataLength+HL,size(watermark,2));
disp(str);
[PSNR_OUT,Z] = psnr(originalImage,watermarkedImage);
str = sprintf('PSNR = %f',PSNR_OUT);
disp(str);
figure,imshow(originalImage,[]),title('Original Image');
figure,imshow(watermarkedImage,[]),title('Watermarked Image');
save WatermarkInfo watermarkedImage watermark BITPLANE_NUMBER WM_SIZE ERROR_NUM originalImage;
% WMI = imread('Watermarked Image.bmp');
% difference = double(watermarkedImage) - double(WMI);
% figure,imshow(difference,[]),title('Difference Image');
