I am a beginner in matlab. I just used below code for embedding watermark. Can anybody tell how to extract watermark from this code??

image1=imread('aaa.jpg');
figure,imshow(image1);
title('Original image');
[ori_row,ori_col]=size(image1)
host_length=ori_row*ori_col;
i=1;
j=1;
k=1;
wmimage=imread('hand.jpg')
[wm_row,wm_col] = size(wmimage);
figure,imshow(wmimage); 
title('Watermark image');
wm=dec2bin(wmimage);
wm_length=wm_row*wm_col*8;
host=dec2bin(image1);
counter=0;
while i < host_length
counter=counter+1;
if counter > wm_length
break;
end
host(i,8)=wm(j,k);
k=k+1;
if k>8
k=1;
j=j+1;
end
i=i+1;
end
key1=wm_row
key2=wm_col
im1=bin2dec(host);
im1=reshape(im1,ori_row,ori_col);
image1(1:ori_row,1:ori_col)=im1(1:ori_row,1:ori_col);
display 'After embed';
imwrite(image1,'wmarked.bmp');
figure,imshow(image1);
title('Watermarked image')

[Image Analyst]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup to format your code.

[Walter Roberson]

Cross reference to http://uk.mathworks.com/matlabcentral/answers/225493-can-anybody-explain-what-is-the-logic-of-the-while-loop-which-is-used-in-the-below-code-i-am-a-beg in which the poster asks for the same code to be explained.

Answer 1

[Image Analyst]

Can't really read the code but I see bin2dec() and dec2bin() in there, so maybe you can use bitget(). With the bad indenting, non-descriptive single letter variable names, and lack of comments, I'm not even going to try to understand it, much less formulate some algorithm for undoing whatever it was you did.