insert text as watermark in video( one frame)

Hi every one

I use matlab R2018b, I try to insert a text (converting to binary) in one frame from my video using dct method but I get some problem so I need help

this is my code:

        % Button pushed function: insrerdataButton
        function insrerdataButtonPushed(app, event)
         Msg_bin = app.EditField2.Value;
         couvert = getimage(app.UIAxes2);
         %couvert = rgb2ycbcr(couvert);
         
        
         taille_msg = size(Msg_bin,1)*size(Msg_bin,2);
         n = size(couvert,1);
         m = size(couvert,2);
         
         %définit le cle secret
         %init de la matrice cle que cle(1,1)=1 et cle(2,1)=1
         cle(1,1)=1;
         cle(2,1)=1;
         a = 1;
         b = 1;
         %pour obtenir les donneés de la cle cad les positions de l'image
         for h=2:taille_msg % on commencer par h=2 puisque on fixer que la cle(1,1)=1 et cle(2,1)=1 pour 2'ieme colonne
             a=a+14;%pour le block est de taille 8 et on besoin de 15 pixels pour calculer les block
             if (a+10>n)
                 a=1;
                 b=b+14;
             end
             cle(1,h)=a;
             cle(2,h)=b;
         end
         for i=1:taille_msg
        % cle(1,i):cle(1,i)+7 =(1:8) cle(2,i):cle(2,i)+7=(1:8)...etc
            block(:,:,i)=couvert(cle(1,i):cle(1,i)+7,cle(2,i):cle(2,i)+7);%pour donner les blocks de taille 8*8
         end
         
          %Calcule le DCT de  chaque Block,;
        
        block = zeros(taille_msg);
        dct_image = zeros(taille_msg);
       
        
        for i=1:taille_msg
            dct_image(:,:,i) = dct(block(:,:,i));
            % error dans cette instruction
           
        end
        
        % parcour de msg
        a=1;
        b=1;
        for i=1:taille_msg
            %pour vérifier que B1(u1,v1)=B1(u2,v2) 
            % 3 et 2 sont des m et n (Amn)
            if (dct_image(3,2,i)==dct_image(2,3,i))
                dct_image(3,2,i)=dct_image(3,2,i)+1; 
            end
            % vérifier l'opération de la partie 4 de l'algo
            if dct_image(3,2,i)<dct_image(2,3,i) && Msg_bin(b,a)=='1'     
               valeur= dct_image(3,2,i);
               dct_image(3,2,i)=dct_image(2,3,i);
               dct_image(2,3,i)=valeur;
            else
                if  dct_image(3,2,i)>dct_image(2,3,i) && Msg_bin(b,a)=='0' 
                    valeur= dct_image(3,2,i);
                    dct_image(3,2,i)=dct_image(2,3,i);
                    dct_image(2,3,i)=valeur;
                end
            end
       
        end
     %pour revenir a la ligne 2 de message c a d le parcour de  tt le msg
        if a==7
           a=1;
           b=b+1;
        else
           a=a+1;
        end
        
        %le idct 
        image_marque=couvert;
        %calcule le idct
        % on utilise le idct du matlab 
        for i = 1:taille_msg
            image_marque(cle(1,i):cle(1,i)+7,cle(2,i):cle(2,i)+7)=uint8(idct(dct_image(:,:,i)));
        end
            
        setappdata(0,'cle_kz',cle);
        setappdata(0,'image_kz',image_marque);
    
        imshow(image_marque,'Parent',app.UIAxes3);
    

        end
         

When I push on this button I got that error:

Index in position 3 exceeds array bounds (must not exceed 1).

Error in app1/insrerdataButtonPushed (line 154)
            dct_image(:,:,i) = dct(block(:,:,i));
 
Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 335)
Error while evaluating Button PrivateButtonPushedFcn.

please help and than you

[LEKHCHINE Somia]

No answer !

[Adam Danz]

Check again ;)

[Adam Danz]

LEKHCHINE Somia's answer moved here as a comment.

Hi

I use matlab R2018b

I insert text as watermark in specific frame from video ( using DCT ) but I have some problem

1- I want to replace the original frame by the watermarked frame

2- the text that I can insert just one char

[LEKHCHINE Somia]

2- the text that I can insert just one character (8 binary) how can I insert more

Answer 1

[Adam Danz]

Based on the error message, it appears that "block" is an [m x n x 1] array (or simply, [m x n]).

You're accessing "block" in a for-loop that controls the 3rd index value. So I'm guessing you get this error on the 2nd iteration where i equals 2 (below).

   for i=1:taille_msg
      dct_image(:,:,i) = dct(block(:,:,i));  % ERROR when i==2

Just prior to that for-loop you define "block" as an [m x n] array or zeros. So certainly, the 3rd dimension of "block" cannot be greater than 1.

 block = zeros(taille_msg);

Curiously, you defined "block" earlier in your code within a different for-loop and in this definition, "block" does appear to be 3D [m x n x i] but you're overwriting it with the zeros which makes it 2D. Now it no longer has a 3rd dimension.

   for i=1:taille_msg
      block(:,:,i)=couvert(cle(1,i):cle(1,i)+7,cle(2,i):cle(2,i)+7);   % THIS IS 3D
   end

   % and later...

  block = zeros(taille_msg);   % THIS IS 2D