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Copy pathrecover_jpegrwdc.m
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recover_jpegrwdc.m
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function [recovered_payload, recovered_JPEG] = recover_jpegrwdc(watermarked_JPEG)
DCTQ=watermarked_JPEG.quant_tables{1,1};
watermarked_qc=watermarked_JPEG.coef_arrays{1,1};
% col=watermarked_JPEG.image_height;
% row=watermarked_JPEG.image_width;
order_zig=[1,2,9,17,10,3,4,11,18,25,33,26,19,12,5,6,13,20,27,34,41,49,42,35,28,21,14,7,8,15,22,29,36,43,50,57,58,51,44,37,30,23,16,24,31,38,45,52,59,60,53,46,39,32,40,47,54,61,62,55,48,56,63,64];
%% Read Image
[col row]=size(image);
% if q_factor <50
% s_factor = 5000/q_factor;
% else
% s_factor = 200 - q_factor*2;
% end
%
%
% DCTQ_50 = DCTQ_50*s_factor + 50;
% DCTQ_50 = (DCTQ_50/100);
%
%
% for i = 1:1:8
% for j = 1:1:8
% if DCTQ_50(i,j) <1
% DCTQ_50(i,j) = 1;
% end
% end
% end
% DCTQ=double(uint8(round(DCTQ_50)));
[sorted_list_odd,~]=prediction_list(watermarked_qc,DCTQ,order_zig,1);
%recover
[col, row]=size(watermarked_qc);
flag=0;
payload_length_limit=ceil(log2(col*row/64));
recovered_side_information_payload_size=ones(1,payload_length_limit);
recovered_payload_limit=bi2de(recovered_side_information_payload_size);
side_information_length=0;
recovered_qc=watermarked_qc;
payload_size=0;
recovered_payload=zeros(1,2^payload_length_limit);
for i=1:length(sorted_list_odd)
if flag==0
dc_prediction=sorted_list_odd(i,3);
i1=sorted_list_odd(i,1);
j1=sorted_list_odd(i,2);
if dc_prediction == 0 || dc_prediction == -1
if side_information_length < payload_length_limit
side_information_length=side_information_length+1;
recovered_side_information_payload_size(side_information_length)=0;
if side_information_length ==payload_length_limit
recovered_payload_limit=bi2de(recovered_side_information_payload_size);
end
else
payload_size=payload_size+1;
recovered_payload(payload_size)=0;
if payload_size == recovered_payload_limit/2
flag=1;
end
end
elseif dc_prediction == 1 || dc_prediction == -2
if side_information_length < payload_length_limit
side_information_length=side_information_length+1;
recovered_side_information_payload_size(side_information_length)=1;
if side_information_length ==payload_length_limit
recovered_payload_limit=bi2de(recovered_side_information_payload_size);
end
else
payload_size=payload_size+1;
recovered_payload(payload_size)=1;
if payload_size == recovered_payload_limit/2
flag=1;
end
end
if dc_prediction == 1
recovered_qc(i1,j1)=watermarked_qc(i1,j1)-1;
elseif dc_prediction == -2
recovered_qc(i1,j1)=watermarked_qc(i1,j1)+1;
end
elseif dc_prediction < -1
recovered_qc(i1,j1)=watermarked_qc(i1,j1)+1;
elseif dc_prediction > 1
recovered_qc(i1,j1)=watermarked_qc(i1,j1)-1;
end
end
if i == length(sorted_list_odd) && flag == 0
flag = 2;
pause
end
end
recovered_payload(payload_size+1:end)=[];
%polarity == 0
[sorted_list,~]=prediction_list(recovered_qc,DCTQ,order_zig,0);
flag=0;
%embed even set
for i=1:length(sorted_list)
if flag==0
dc_prediction=sorted_list(i,3);
i1=sorted_list(i,1);
j1=sorted_list(i,2);
if dc_prediction == 0 || dc_prediction == -1
payload_size=payload_size+1;
recovered_payload(payload_size)=0;
if payload_size == recovered_payload_limit
flag=1;
end
elseif dc_prediction == 1 || dc_prediction == -2
payload_size=payload_size+1;
recovered_payload(payload_size)=1;
if payload_size == recovered_payload_limit
flag=1;
end
if dc_prediction == 1
recovered_qc(i1,j1)=watermarked_qc(i1,j1)-1;
elseif dc_prediction == -2
recovered_qc(i1,j1)=watermarked_qc(i1,j1)+1;
end
elseif dc_prediction < -1
recovered_qc(i1,j1)=watermarked_qc(i1,j1)+1;
elseif dc_prediction > 1
recovered_qc(i1,j1)=watermarked_qc(i1,j1)-1;
end
end
end
temp_payload=[recovered_payload(recovered_payload_limit/2+1:end) recovered_payload(1:recovered_payload_limit/2)];
recovered_payload=temp_payload;
recovered_JPEG=watermarked_JPEG;
recovered_JPEG.coef_arrays=mat2cell(recovered_qc,col,row);
end
function [sorted_list,zig_zag_coeff]=prediction_list(TQ,DCTQ,order_zig,polarity)
p_reconstructed=zeros(size(TQ,1),size(TQ,2));
reconstructed=zeros(size(TQ,1),size(TQ,2));
zig_zag_coeff=zeros(size(TQ,1)/64*size(TQ,2),64);
DC_p=zeros(size(TQ,1)/64*size(TQ,2),1);
DC_p2=zeros(size(TQ,1)/64*size(TQ,2),1);
Dpcm=zeros(size(TQ,1)/64*size(TQ,2),1);
dctmtx_8=dctmtx(8);
sorted_list=zeros(size(TQ,1)/64*size(TQ,2),4);
P_TQ=zeros(size(TQ,1),size(TQ,2));
DC_p3=zeros(size(TQ,1)/64*size(TQ,2),1);
for index_i=1:size(TQ,1)/8
for index_j=1:size(TQ,2)/8
i=1+8*(index_i-1);
j=1+8*(index_j-1);
reconstructed(i:i+7,j:j+7)=round(dctmtx_8'*(TQ(i:i+7,j:j+7).*DCTQ)*dctmtx_8)+128;
k=index_j+(index_i-1)*size(TQ,2)/8;
temp_tq=reshape(TQ(i:i+7,j:j+7)',1,64);
zig_zag_coeff(k,:)=temp_tq(order_zig);
P_TQ(i:i+7,j:j+7)=TQ(i:i+7,j:j+7);
P_TQ(i,j)=0;
p_reconstructed(i:i+7,j:j+7)=round(dctmtx_8'*(P_TQ(i:i+7,j:j+7).*DCTQ)*dctmtx_8)+128;
end
end
k=0;
previous_DC=0;
for index_i=1:size(TQ,1)/8
for index_j=1:size(TQ,2)/8
i=1+8*(index_i-1);
j=1+8*(index_j-1);
current_qc=TQ(i:i+7,j:j+7);
if mod(index_i+index_j,2)==polarity
k=k+1;
%First block
if i==1 && j==1
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1);
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1);
%Top right corner
elseif i==1 && j==size(TQ,2)-7
W=double(reconstructed(i:i+7,j-8:j-1));
S=double(reconstructed(i+8:i+15,j:j+7));
current_p=p_reconstructed(i:i+7,j:j+7);
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([W(:,8)-current_p(:,1); S(1,:)'-current_p(8,:)'])*8/DCTQ(1,1));
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
%Bottom left corner
elseif i==size(TQ,1)-7 && j==1
N=double(reconstructed(i-8:i-1,j:j+7));
E=double(reconstructed(i:i+7,j+8:j+15));
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([N(8,:)'-current_p(1,:)'; E(:,1)-current_p(:,8)])*8/DCTQ(1,1));
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
%Bottom right corner
elseif i==size(TQ,1)-7 && j==size(TQ,2)-7
N=double(reconstructed(i-8:i-1,j:j+7));
W=double(reconstructed(i:i+7,j-8:j-1));
current_p=p_reconstructed(i:i+7,j:j+7);
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([W(:,8)-current_p(:,1); N(8,:)'-current_p(1,:)'])*8/DCTQ(1,1));
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
%Top line
elseif i==1
W=double(reconstructed(i:i+7,j-8:j-1));
E=double(reconstructed(i:i+7,j+8:j+15));
S=double(reconstructed(i+8:i+15,j:j+7));
current_p=p_reconstructed(i:i+7,j:j+7);
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([W(:,8)-current_p(:,1); E(:,1)-current_p(:,8); S(1,:)'-current_p(8,:)'])*8/DCTQ(1,1));
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
%Left line
elseif j==1
N=double(reconstructed(i-8:i-1,j:j+7));
E=double(reconstructed(i:i+7,j+8:j+15));
S=double(reconstructed(i+8:i+15,j:j+7));
current_p=p_reconstructed(i:i+7,j:j+7);
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([N(8,:)'-current_p(1,:)'; E(:,1)-current_p(:,8); S(1,:)'-current_p(8,:)'])*8/DCTQ(1,1));
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
%Right line
elseif j== size(TQ,2)-7
N=double(reconstructed(i-8:i-1,j:j+7));
W=double(reconstructed(i:i+7,j-8:j-1));
current_p=p_reconstructed(i:i+7,j:j+7);
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([W(:,8)-current_p(:,1); N(8,:)'-current_p(1,:)'])*8/DCTQ(1,1));
%Bottom line
elseif i== size(TQ,1)-7
N=double(reconstructed(i-8:i-1,j:j+7));
W=double(reconstructed(i:i+7,j-8:j-1));
E=double(reconstructed(i:i+7,j+8:j+15));
current_p=p_reconstructed(i:i+7,j:j+7);
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([W(:,8)-current_p(:,1); N(8,:)'-current_p(1,:)'; E(:,1)-current_p(:,8)])*8/DCTQ(1,1));
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
%Rest
else
N=double(reconstructed(i-8:i-1,j:j+7));
W=double(reconstructed(i:i+7,j-8:j-1));
E=double(reconstructed(i:i+7,j+8:j+15));
S=double(reconstructed(i+8:i+15,j:j+7));
current_p=p_reconstructed(i:i+7,j:j+7);
DC_p3(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-round(mean([W(:,8)-current_p(:,1); N(8,:)'-current_p(1,:)'; E(:,1)-current_p(:,8); S(1,:)'-current_p(8,:)'])*8/DCTQ(1,1));
Dpcm(index_j+(index_i-1)*size(TQ,2)/8)=current_qc(1,1)-previous_DC;
end
sorted_list(k,:)=[i,j,DC_p3(index_j+(index_i-1)*size(TQ,2)/8),sum(zig_zag_coeff(k,2:end)==0)];
end
previous_DC=current_qc(1,1);
end
end
sorted_list=sorted_list(1:k,:);
sorted_list=sortrows(sorted_list,-4);
% sorted_list2=sortrows(sorted_list2,-4);
% sorted_list3=sortrows(sorted_list3,-4);
end