基于混沌和位运算的图像加密算法的改进算法和性能分析.doc

%改进算法，及性能分析
clear
clc
a=imread('rice.png');
a=double(a);
[m1,n1]=size(a);
b=zeros(m1,n1*8);
fori=1:1:m1
forj=1:1:n1
fort=0:1:7
ifmod(floor(a(i,j)/2^t),2)==1
b(i,j*8-t)=1;
else
b(i,j*8-t)=0;
end
end
end
end
q=4;
b1=b;
x1(1)=0.3333;
forn=1:n1*8+100
x1(n+1)=q*x1(n)*(1-x1(n));
end
n=101:1:n1*8+100;
y1(n-100)=x1(n);
[z1,l1]=sort(y1,2);
fori=1:1:n1*8
b1(:,i)=b(:,l1(i));
end
x2(1)=0.4444;
form=1:m1+100
x2(m+1)=q*x2(m)*(1-x2(m));
end
m=101:1:m1+100;
y2(m-100)=x2(m);
[z2,l2]=sort(y2,2);
fori=1:1:m1
b(i,:)=b1(l2(i),:);
end
fori=1:1:m1
forj=1:1:n1
a(i,j)=b(i,j*8);
fort=1:1:7
a(i,j)=a(i,j)+2^t*b(i,j*8-t);
end
end
end
a=uint8(a);
figure,imshow(a);
figure,imhist(a);
a=double(a);
g(1)=0.5555;%混沌序列的初始值
fori=1:1:256*256%改进算法
t(i)=mod(floor(g(i)*10^3),256);%
ifg(i)<0.5
g(i+1)=4*q*g(i)*(0.5-g(i));
else
g(i+1)=1-4*q*(g(i)-0.5)*(1-g(i));
end
end
t=reshape(t,256,256);
t=t';
fori=1:1:256
forj=1:1:256
s1(i,j)=mod((a(i,j)+t(i,j)*abs(i-j)),256);
end
end
s1=uint8(s1);
figure,imshow(s1);%显示加密图像
figure,imhist(s1);%加密图像灰度值
s1=double(s1);%解密是加密的反
fori=1:1:256
forj=1:1:256
a(i,j)=mod((s1(i,j)-t(i,j)*abs(i-j)),256);
end
end
fori=1:1:m1
forj=1:1:n1
fort=0:1:7
ifmod(floor(a(i,j)/2^t),2)==1
b(i,j*8-t)=1;
else
b(i,j*8-t)=0;
end
end
end
end
fori=1:1:m1
b1(l2(i),:)=b(i,:);
end
fori=1:1:n1*8
b(:,l1(i))=b1(:,i);
end
fori=1:1:m1
forj=1:1:n1
a(i,j)=b(i,j*8);
fort=1:1:7
a(i,j)=a(i,j)+2^t*b(i,j*8-t);
end
end
end
a=uint8(a);
figure,imshow(a);

%求灰度值差异
clear
clc
a=imread('rice.png');
[m1,n1]=size(a);
a=double(a);
gn=zeros(m1-2,n1-2);%定义（m1-2）*（n1-2）的矩阵
fori=2:1:255%计算每个与其他四个相邻像素灰度值的差异
forj=2:1:255
am=(a(i,j)-a(i-1,j))^2;
am=am+(a(i,j)-a(i+1,j))^2;
am=am+(a(i,j)-a(i,j-1))^2;
am=am+(a(i,j)-a(i,j+1))^2;
gn(i-1,j-1)=am/4;
end
end
am=0;
fori=1:1:254
forj=1:1:254
am=gn(i,j)+am;
end
end
an=am/((m1-2)*(n1-2));

%求各图像的相关性
k1=unidrnd(255,1,20);%生成1*20的矩阵，由[1,255]之间的数组成
k2=randint(1,50,[1,255]);%生成1*50的矩阵，由[1,255]之间的数组成
fori=1:50
forj=1:20
x(i,j)=s1(k2(i),k1(j));
y(i,j)=s1(k2(i),k1(j)+1);%%水平相关性
%y(i,j)=s1(k2(i)+1,k1(j));%