How to reduce code execution time ?

 clc;
 clear all;

 %secret image
 a=imread('secret1.bmp');
 %a=rgb2gray(a);
 a=a(:,:,1);
 figure,
 imshow(a);
 title('secret image'); 

 %cover image1
 b=imread('secret2.bmp');
%b=rgb2gray(b);
b=b(:,:,1);
figure,
imshow(b);
title('Cover image 1');

 %cover image2
e=imread('secret3.bmp');
e=e(:,:,1);
figure,
imshow(e);
title('Cover image 2');

 d=uint8(zeros(size(a)));

 %output
 for i=1:256;
for j=1:256;
d(i,j)=bitset(d(i,j),8,bitget(e(i,j),8));
h=fi(b(i,j),0,8,0);
       %b=bin(a);
k(i,j)=bitror(h,1);
g(i,j)= uint8(k(i,j));
d(i,j)=bitset(d(i,j),7,bitget(bitxor(a(i,j),(g(i,j))),7));
d(i,j)=bitset(d(i,j),6,bitget(bitxor(a(i,j),(g(i,j))),6));
d(i,j)=bitset(d(i,j),5,bitget(bitxor(a(i,j),(g(i,j))),5));
d(i,j)=bitset(d(i,j),4,bitget(bitxor(a(i,j),(g(i,j))),4));
d(i,j)=bitset(d(i,j),3,bitget(bitxor(a(i,j),(g(i,j))),3));
d(i,j)=bitset(d(i,j),2,bitget(bitxor(a(i,j),(g(i,j))),2));
d(i,j)=bitset(d(i,j),1,bitget(bitxor(a(i,j),(g(i,j))),1));
end
end
figure,
imshow(d);
title('output');

Above image Pixels having 8bits. I want to Read 1 to 7 BITS of Image1, and 8th BIT from Image2. And create a New Image then i want to Hide Image3 in Newly Created Image and want to Generate Output. Code for same is working very slow.! Please suggest to do fast operation.

[KALYAN ACHARJYA]

Attach the images, so that we can try, What is the execution time in your case? use tic toc. Try to avoid multiple for loops