加密部分
A=imread('~/Desktop/11.jpg');
C=imread('~/Desktop/11.jpg');
C=rgb2gray(C);
A=rgb2gray(A);
imshow(A);
for k=1:50
for x=1:508
for y=1:508
x1=x y;
y1=x 2*y;
if(x1>508)
x1=mod(x1,508);
end
if(y1>508)
y1=mod(y1,508);
end
if x1==0
x1=508;
end
if y1==0
y1=508;
end
B(x1,y1)=A(x,y);
end
end
A=B;
if(A==C)
d=k;
end
end
imshow(B);
imwrite(B,'111.png');