can anybody reframe this code to watermark an rgb image into an rgb

clear all;
close all;
x=double(imread('greens.jpg'));
figure;
imshow(x/255);
y=x;
a=zeros(300,500);
% (imread('l.jpg'));
a(100:250,100:350)=1;
figure;
imshow(a);
save m.dat a -ascii
x1=x(:,:,1);
x2=x(:,:,2);
x3=x(:,:,3);
dx1=dct2(x1);dx11=dx1;
dx2=dct2(x2);dx22=dx2;
dx3=dct2(x3);dx33=dx3;
 load m.dat
g=100;  
[rm,cm]=size(m);
dx1(1:rm,1:cm)=dx1(1:rm,1:cm)+g*m;
dx2(1:rm,1:cm)=dx2(1:rm,1:cm)+g*m;
dx3(1:rm,1:cm)=dx3(1:rm,1:cm)+g*m;
figure,imshow(dx1);
figure,imshow(dx2);
figure,imshow(dx3);
y1=idct2(dx1);
y2=idct2(dx2);
y3=idct2(dx3);
y(:,:,1)=y1;
y(:,:,2)=y2;
y(:,:,3)=y3;
figure;imshow(y1);
figure;imshow(y2);
figure;imshow(y3);
figure;imshow(y/255);
figure;imshow(abs(y-x)*100);
z=y;
[r,c,s]=size(z);
dy1=dct2(y(:,:,1));
dy2=dct2(y(:,:,2));
dy3=dct2(y(:,:,3));
y=z;
dy1(1:rm,1:cm)=dy1(1:rm,1:cm)-g*m;
dy2(1:rm,1:cm)=dy2(1:rm,1:cm)-g*m;
dy3(1:rm,1:cm)=dy3(1:rm,1:cm)-g*m;
y11=idct2(dy1);
y22=idct2(dy2);
y33=idct2(dy3);
yy(:,:,1)=y11;
yy(:,:,2)=y22;
yy(:,:,3)=y33;
figure;
imshow(yy/255);
figure;
imshow(abs(yy-x)*10000);

[Rik]

You should really add some comments to this code. A good rule of thumb is to try to make half of all characters in your code green. You will probably not write that much comments, but trying to will result in complete comments.

It is not clear to me what the purpose of this code is. Reading the title I expected something related to imfuse.