%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%反LSB隐写算法
%采用直方图补偿算法
%前面一半数据进行数据隐写，后面的数据进行直方图补偿
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function backLsbHide(imgName,file,output)
%读入图像
img = imread(imgName);
%显示图像
figure();
subplot(121);
imshow(img);title('原图');
%将文本文件转化为二进制序列
f_id = fopen(file,'r');
[msg,len] = fread(f_id,'ubit1');
%将图像通道分离出来,这里主要用r通道
r = img(:,:,1); %通道R
g = img(:,:,2); %通道G
b = img(:,:,3); %通道B
%保存灰度图
suffix = strsplit(imgName,'.');
if suffix{2} == 'jpg'
filename1 = 'r1.jpg'
filename2 = 'r2.jpg'
filename3 = 'fina.jpg'
else
filename1 = 'r1.bmp'
filename2 = 'r2.bmp'
filename3 = 'fina.bmp'
end
outputname = strcat(output,filename1);
imwrite(r,outputname);
%判断信息量是否过大
[m,n] = size(r)
if len>m*n/2
error('嵌入信息量过大');
end
%P作为记数器
r1 = double(r);
r_double = r1;
n1 = n/2;
p=1;
for f1=1:n1
for f2=1:m
for f3=1:m
if r1(f1,f2) == r1(f1+n1,f3)
r1(f1,f2) = r1(f1,f2) - mod(r1(f1,f2),2) + msg(p,1);
if r1(f1+n/2,f3)>r1(f1,f2)
r1(f1+n/2,f3) = mod(r1(n1,f3),2)+1;
elseif r1(f1+n/2,f3)<r1(f1,f2)
r1(f1+n/2,f3) = mod(r1(n1,f3),2)-1;
end
break;
end
end
if p == len
break;
end
p = p + 1;
end
if p == len
break;
end
end
outputname = strcat(output,filename2);
r_int=uint8(r1);
imwrite(r_int,outputname);
%通道合并
img_1(:,:,1)=r1;
img_1(:,:,2)=g;
img_1(:,:,3)=b;
subplot(122);
imshow(img_1);title("反隐写图像");
outputname = strcat(output,filename3);
imwrite(img_1,outputname);
figure();
r_double = double(r_double)/255;
r1 = double(r1)/255;
F = r1 - r_double;
imshow(mat2gray(F));
end
