Broken code:visual cryptography

The code is:

clc;
clear all;
i=imread('lena256x256.jpg');
i=im2bw(i,0.3);
s=size(i);
a=s(1);
b=s(2);
s1a=[1 0;1 0];
part1=zeros(a,2*b);
part2=zeros(a,2*b);
[x y]=find(i==1);
len=length(x);
for I=1:len
  a1=x(I);b1=y(I);
  part1((a1),(2*b1-1):(2*b1))=s1a(1,1:2);
  part2((a1),(2*b1-1):(2*b1))=s1a(2,1:2);
end
[x y]=find(i==0);
len=length(x);
s1a=[1 0;0 1];
for I=1:len
  a1=x(I);b1=y(I);
  part1((a1),(2*b1-1):(2*b1))=s1a(1,1:2);
  part2((a1),(2*b1-1):(2*b1))=s1a(2,1:2);
end
decrypt=bitor(part1,part2);
decrypt=~decrypt;
figure;imshow(decrypt);
figure;imshow(part1);
figure;imshow(part2);

Images of each part, decrypted image and original image are attached.

Thank you!