Can anyone explain the code I have given for visual cryptography?

Question

Mangai s 2017-2-22

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/326312-can-anyone-explain-the-code-i-have-given-for-visual-cryptography

评论： Walter Roberson 2017-2-22

This is the main program:

clc;
clear all;
close all;
tic;
%Input
inImg = imread('D:\our project\crypt\lena.bmp');
inImg=im2double(imresize(inImg,0.5));
figure
imshow(inImg);
inImg=im2bw(inImg);
%inImg=double(inImg);
figure
imshow(inImg);
title('Secret Image');
%fn call
[share1, share2, share12] = VisCrypt(inImg);
toc;
%Output
share1 = imresize(share1, [256 256]);
%share1=im2double(imresize(share1,0.5,'nearest'));
figure
imshow(share1);
title('Share 1');
share2 = imresize(share2, [256 256]);
figure
imshow(share2);
title('Share 2');
share12 = imresize(share12, [256 256]);
figure;imshow(share12);title('Overlapping Share 1 & 2');
imwrite(share1,'Share1.jpg');
imwrite(share2,'Share2.jpg');
imwrite(share12,'Overlapped.jpg');

This function is to generate shares:

function out = generateShare(a,b)
a1 = a(1);
a2 = a(2);
b1 = b(1);
b2 = b(2);
in = [a
      b];
out = zeros(size(in));
randNumber = floor(1.9*rand(1));
if (randNumber == 0)
    out = in;
elseif (randNumber == 1)
    a(1) = a2;
    a(2) = a1;
    b(1) = b2;
    b(2) = b1;
    out = [a
           b];   
end

This function generates the splitting of black and white pixel:

function [share1, share2, share12] = VisCrypt(inImg)
s = size(inImg);
share1 = zeros(s(1), (2 * s(2)));
share2 = zeros(s(1), (2 * s(2)));
%%White Pixel 
s1a=[1 0];
s1b=[1 0];
[x y] = find(inImg == 1);
len = length(x);
for i=1:len
    a=x(i);b=y(i);
    pixShare=generateShare(s1a,s1b);
    share1((a),(2*b-1):(2*b))=pixShare(1,1:2);
    share2((a),(2*b-1):(2*b))=pixShare(2,1:2);
end
%Black pixel
s0a=[1 0];
s0b=[0 1];
[x y] = find(inImg == 0);
len = length(x);
for i=1:len
    a=x(i);b=y(i);
    pixShare=generateShare(s0a,s0b);
    share1((a),(2*b-1):(2*b))=pixShare(1,1:2);
    share2((a),(2*b-1):(2*b))=pixShare(2,1:2);
end
share12=bitor(share1, share2);
   share12= ~share12;