JPEGEncodeDecode.m

function JPEGEncodeDecode

img=imread('original.jpg');
% img = img(1:16,1:16,:);

% subplot(121);imshow(img);title('原图');         %显示原图

img_ycbcr = rgb2ycbcr(img);            % rgb->yuv转换

[row,col,~]=size(img_ycbcr);      % 取出行列数，~表示3个通道算1列

%对图像进行扩展

row_expand=ceil(row/16)*16;       %行数上取整再乘16，及扩展成16的倍数

if mod(row,16)~=0           %行数不是16的倍数，用最后一行进行扩展

   for i=row:row_expand

       img_ycbcr(i,:,:)=img_ycbcr(row,:,:);

   end

end

col_expand=ceil(col/16)*16; %列数上取整

if mod(col,16)~=0        %列数不是16的倍数，用最后一列进行扩展

   for j=col:col_expand

       img_ycbcr(:,j,:)=img_ycbcr(:,col,:);

   end

end

 
%对Y,Cb,Cr分量进行4:2:2采样

Y=img_ycbcr(:,:,1);                   %Y分量

Cb=zeros(row_expand/2,col_expand/2);       %Cb分量

Cr=zeros(row_expand/2,col_expand/2);       %Cr分量

for i=1:row_expand/2

    for j=1:2:col_expand/2-1         %奇数列

       Cb(i,j)=double(img_ycbcr(i*2-1,j*2-1,2));     

       Cr(i,j)=double(img_ycbcr(i*2-1,j*2+1,3));     

   end

end

for i=1:row_expand/2

    for j=2:2:col_expand/2           %偶数列

       Cb(i,j)=double(img_ycbcr(i*2-1,j*2-2,2));     

       Cr(i,j)=double(img_ycbcr(i*2-1,j*2,3));     

   end

end


%分别对三种颜色分量进行编码

Y_Table=[16 11  10  16 24  40  51 61

   12  12  14 19  26  58 60  55

   14  13  16 24  40  57 69  56

   14  17  22 29  51  87 80  62

   18  22  37 56  68 109 103 77

   24  35  55 64  81 104 113 92

   49  64  78  87 103 121 120 101

   72  92  95  98 112 100 103  99];%亮度量化表

CbCr_Table=[17, 18, 24, 47, 99, 99, 99, 99;

   18, 21, 26, 66, 99, 99, 99, 99;

   24, 26, 56, 99, 99, 99, 99, 99;

   47, 66, 99 ,99, 99, 99, 99, 99;

   99, 99, 99, 99, 99, 99, 99, 99;

   99, 99, 99, 99, 99, 99, 99, 99;

   99, 99, 99, 99, 99, 99, 99, 99;

    99, 99, 99, 99, 99, 99, 99, 99];%色差量化表


Qua_Factor=80;%量化因子,最小为0.01,最大为255,建议在0.5和3之间,越小质量越好文件越大

%对三个通道分别DCT和量化

Y_dct_q=Dct_Quantize(Y,Qua_Factor,Y_Table);

Cb_dct_q=Dct_Quantize(Cb,Qua_Factor,CbCr_Table);

Cr_dct_q=Dct_Quantize(Cr,Qua_Factor,CbCr_Table);
k = 50;
p = 1;
thr = 3;
colt = zeros([2 28]);
colt(1,:) = [8,8,7,8,7,6,8,7,6,5,8,7,6,5,4,8,7,6,5,4,3,8,7,6,5,4,3,2];
colt(2,:) = [8,7,8,6,7,8,5,6,7,8,4,5,6,7,8,3,4,5,6,7,8,2,3,4,5,6,7,8];
ws = 7;
% [Y1,res1] = Embedding(Y_dct_q,Y_Table,k,p,colt,ws);
% if any(any(Cr_dct_q))
%     [Cr1,res2] = Embedding(Cr_dct_q,CbCr_Table,k,p,colt,ws);
% else
%     Cr1 = Cr_dct_q;
% end
% if any(any(Cb_dct_q))
%     [Cb1,res3] = Embedding(Cb_dct_q,CbCr_Table,k,p,colt,ws);
% else
%     Cb1 = Cb_dct_q;
% end

% Y2 = Extraction(Y1,k,p,colt,ws,res1);
% if any(any(Cr1))
%     Cr2 = Extraction(Cr1,k,p,colt,ws,res2);
% else
%     Cr2 = Cr1;
% end
% if any(any(Cb1))
%     Cb2 = Extraction(Cb1,k,p,colt,ws,res3);
% else
%     Cb2 = Cb1;
% end
% if ~isequal(Y_dct_q,Y2) %|| ~isequal(Cr_dct_q,Cr2) || ~isequal(Cb_dct_q,Cb2)
%     return
% end

key = 1;
Y_enc = Encryption(Y_dct_q,key,2^thr);
Cr_enc = Encryption(Cr_dct_q,key,2^thr);
Cb_enc = Encryption(Cb_dct_q,key,2^thr);
% % % Inverse
% % Y_enc = Encryption(Y_enc,key,thr);
% % Cb_enc = Encryption(Cb_enc,key,thr);
% % Cr_enc = Encryption(Cr_enc,key,thr);
% % 对三个通道分别反量化和反DCT
Y_in_q_dct=Inverse_Quantize_Dct(Y_enc,Qua_Factor,Y_Table);
Cb_in_q_dct=Inverse_Quantize_Dct(Cb_enc,Qua_Factor,CbCr_Table);
Cr_in_q_dct=Inverse_Quantize_Dct(Cr_enc,Qua_Factor,CbCr_Table);
% Y_in_q_dct=Inverse_Quantize_Dct(Y_dct_q,Qua_Factor,Y_Table);
% Cb_in_q_dct=Inverse_Quantize_Dct(Cb_dct_q,Qua_Factor,CbCr_Table);
% Cr_in_q_dct=Inverse_Quantize_Dct(Cr_dct_q,Qua_Factor,CbCr_Table);

%恢复出YCBCR图像

YCbCr_in(:,:,1)=Y_in_q_dct;

for i=1:row_expand/2

   for j=1:col_expand/2

       YCbCr_in(2*i-1,2*j-1,2)=Cb_in_q_dct(i,j);

       YCbCr_in(2*i-1,2*j,2)=Cb_in_q_dct(i,j);

       YCbCr_in(2*i,2*j-1,2)=Cb_in_q_dct(i,j);

       YCbCr_in(2*i,2*j,2)=Cb_in_q_dct(i,j);

       
       YCbCr_in(2*i-1,2*j-1,3)=Cr_in_q_dct(i,j);

       YCbCr_in(2*i-1,2*j,3)=Cr_in_q_dct(i,j);

       YCbCr_in(2*i,2*j-1,3)=Cr_in_q_dct(i,j);

       YCbCr_in(2*i,2*j,3)=Cr_in_q_dct(i,j);

   end

end

I_in=ycbcr2rgb(YCbCr_in);

I_in(row+1:row_expand,:,:)=[];%去掉扩展的行

I_in(:,col+1:col_expand,:)=[];%去掉扩展的列


I_th = Thumbnail(I_in,8);

subplot(122);imshow(I_th);title('加密后的图片');
imwrite(I_in,'result.jpg');


% Y_enc = Encryption(Y_dct_q,key,thr);
% Cb_enc = Encryption(Cb_dct_q,key,thr);
% Cr_enc = Encryption(Cr_dct_q,key,thr);
% Y_in_q_dct=Inverse_Quantize_Dct(Y_enc,Qua_Factor,Y_Table);
% Cb_in_q_dct=Inverse_Quantize_Dct(Cb_enc,Qua_Factor,CbCr_Table);
% Cr_in_q_dct=Inverse_Quantize_Dct(Cr_enc,Qua_Factor,CbCr_Table);
% 
% %恢复出YCBCR图像
% 
% YCbCr_in(:,:,1)=Y_in_q_dct;
% 
% for i=1:row_expand/2
% 
%    for j=1:col_expand/2
% 
%        YCbCr_in(2*i-1,2*j-1,2)=Cb_in_q_dct(i,j);
% 
%        YCbCr_in(2*i-1,2*j,2)=Cb_in_q_dct(i,j);
% 
%        YCbCr_in(2*i,2*j-1,2)=Cb_in_q_dct(i,j);
% 
%        YCbCr_in(2*i,2*j,2)=Cb_in_q_dct(i,j);
% 
%        
%        YCbCr_in(2*i-1,2*j-1,3)=Cr_in_q_dct(i,j);
% 
%        YCbCr_in(2*i-1,2*j,3)=Cr_in_q_dct(i,j);
% 
%        YCbCr_in(2*i,2*j-1,3)=Cr_in_q_dct(i,j);
% 
%        YCbCr_in(2*i,2*j,3)=Cr_in_q_dct(i,j);
% 
%    end
% 
% end
% 
% I_in=ycbcr2rgb(YCbCr_in);
% 
% I_in(row+1:row_expand,:,:)=[];%去掉扩展的行
% 
% I_in(:,col+1:col_expand,:)=[];%去掉扩展的列
% I_th = Thumbnail(I_in,8);
% subplot(121);imshow(I_th);title('重构后的图片');
% imwrite(I_in,'result1.jpg');
% % 
% [M,N,C] = size(img);
% for c = 1 : C
%     for i = 1 : M
%         for j = 1 : N
%             if img(i,j,c)~=I_in(i,j,c)
%                 i,j,c
%                 break
%             end
%         end
%     end
% end

end