add text to photos please check my code, latest_dat​a(i,j,k)=c​andidate_I​mage(i,j,k​)-mod(cand​idate_Imag​e(i,j,k),2​)+M(count,​1);

candidate_Image=('apa.jpg'); %load the image
M = 'rahasia.txt'
rahasia=fopen (M,'rb'); %open secret file
[M,L] = fread(rahasia,'ubit1'); %read secret file as bin array
% L is the length of secret file
[n,m]=size(candidate_Image); %n is width, m is height*3
m=m/3;
%m*n is the max size to save secret
if (m*n*3<L)
    msg=msgbox('your picture is too small','size error','modal');
    pause (1);
    if (ishandle (msg))
        close (msg);
    end
end
latest_data=candidate_Image;
count=1;

for i=1:m %width
    for j=1:n %height
        for k=1:3 %RGB
            latest_data(i,j,k)=candidate_Image(i,j,k)-mod(candidate_Image(i,j,k),2)+M(count,1);
            if count==L
                break;
            end
            count=count+1;
        end
        if count==L
            break;
        end
    end
    if (L==count)
        break;
    end
end

imwrite(latest_data, 'encrypted_Image.jpg', 'bmp');

CC=M;
countl=l;
for i=l:m
    for j=l:n
        for k=l:3
            CC(countl)=latest_data(i,j,k)-candidate_Image(i,j,k);
            if countl==L
                break
            end
            countl=countl+l
        end
        if countl==L
            break
        end
    end
    if countl==L
        break
    end
end

Answer 1

[Image Analyst]

What does that way under-commented code do? Is it steganography where you're hiding/encoding text in the image pixels? If so, see my attached example.

[ahmad assahab]

That's right, steganography techniques, can you explain how your code nets

[Image Analyst]

I did explain it! Did you actually look at the code? I'm not your garden variety, typical programmer like you usually see here. I have very descriptive variable names that practically comment the code themselves. And if that's not enough, about half the lines in that script are comments that actually explain in detail what the code is doing.

I ran my attached comment_counter program and it says:

In file hide_text_in_image, found 262 lines total. Of those, 124, or 47.33% were comment lines.

I seriously don't know what other explanations I can add, but if you think of any, let me know and I'll add more explanatory comments.

[ahmad assahab]

It says "Specify where the demo folder (works with all versions)." Can I change my folder, or can only use the demo folder?

Can the image that we inserted the text be saved?

[Image Analyst]

That sets the folder to the folder where the demo images are that ship with MATLAB. You can change it to whatever you want. Replace it with

folder = uigetdir();

or

startingFolder = 'c:/users/ahmad/wherever you want';
folder = uigetdir(startingFolder);

You can save the stego image if you want:

% Get the name of the file that the user wants to save.
% Note, if you're saving an image you can use imsave() instead of uiputfile().
startingFolder = userpath % Or "pwd" or wherever you want.
defaultFileName = fullfile(startingFolder, '*.*');
[baseFileName, folder] = uiputfile(defaultFileName, 'Specify a file');
if baseFileName == 0
	% User clicked the Cancel button.
	return;
end
fullFileName = fullfile(folder, baseFileName)
imwrite(stegoImage, fullFileName);

[ahmad assahab]

Thank you very much

[ahmad assahab]

how about coding an affine cipher that hides text to image files?