how to recoup a watermark image !

clear all; close all; clc;
mat=imread('cameraman.tif');
watermark=imread('cameraman.tif');%% watermark
B2=im2bw(watermark);%% watermark en binair
Marque_V=B2(:);%% vecteur
bitplandepth=1
matW = Wnsrtion(mat,Marque_V,bitplandepth);%% insertion dans mat
subplot(1,2,1)
imshow(mat)
title('image original')
subplot(1,2,2)
imshow(matW)
title('image tatouée')
t=all(all(mat==matW))
psnr =calcul_psnr(mat,matW)
%%extraction
Lbits=length(Marque_V);
Marque_V_recup = extractw( matW,bitplandepth,Lbits );


the function "Wnsrtion()"
function [matW ] = Wnsrtion(mat,Marque_V,bitplandepth)
[L,C]=size(mat)
matv=mat(:);
matvW=matv;
bitplan=1
for i=1:length(Marque_V)
    matvW(i)=bitset(matv(i),bitplan,Marque_V(i));
end
matW=reshape(matvW,[C,L]);
 
end

the function "extractw()"
function [Marque_V_recup] = extractw( matW,bitplandepth,Lbits )
[n,m]=size(matW);
pitplandepth=1;
matV=matW(:);
for i=1:Lbits
 Marque_V_recup(i) =bitget(matV(i),bitplandepth);
end

[DGM]

It may be safe to assume that this is some form of LSB watermarking, but without knowing how the data is being manipulated, it's not possible to instruct how the process should be reversed.

Nobody can guess precisely what the user-defined functions Wnsrtion() and extractw() do, so unless you provide that information, the implied question is not answerable.

Answer 1

[DGM]

Try this.

mat = imread('cameraman.tif'); % host image
watermark = imread('cameraman.tif'); % payload image

B2 = im2bw(watermark); % watermark en binair
Marque_V = B2(:); % vecteur
bitplandepth = 1;
matW = Wnsrtion(mat,Marque_V,bitplandepth); % insertion dans mat

subplot(1,2,1)
imshow(mat)
title('image original')

subplot(1,2,2)
imshow(matW)
title('image tatouée')

%t = all(all(mat==matW))
%psnr = calcul_psnr(mat,matW)

Lbits = numel(Marque_V);
Marque_V_recup = extractw(matW,bitplandepth,Lbits);
arraysaresame = all(Marque_V == Marque_V_recup) % vectors are equal

% if you want to reshape it into a 2D image
B2_recovered = reshape(Marque_V_recup,size(B2));


function [mat] = Wnsrtion(mat,Marque_V,bitplandepth)
    nel = numel(Marque_V);
    samp = mat(1:nel);
    mat(1:nel) = bitset(samp(:),bitplandepth,Marque_V(:));
end

function [Marque_V_recup] = extractw(matW,bitplandepth,Lbits)
    Marque_V_recup = logical(bitget(matW(1:Lbits),bitplandepth));
    Marque_V_recup = Marque_V_recup(:);
end