Ask about extraction watermark SVD

i have problem about extract waatermark using SVD

here is my code

clc

close all;

a=0.0010

I=imread('citra.jpg'); %Image Host

I=rgb2gray(I);

II=im2double(I);

[U,S,V]=svd(II);

M=imread('logoUPN.jpg'); %Image Watermark

M=rgb2gray(M)

W=im2double(M);

%Embedding St = S + a * W;

AW = U * St * V';

imwrite(AW,'watermarked.jpg');

%Extract IW =imread('watermarked.jpg'); WW = im2double(IW);

ST=U' * WW * V;

Ww=(ST-Siga)/a;

figure,imshow(AW);

figure,imshow(Ww);

extracting image is so blurrr and not clear i want to make two menu embedding and extraction

please help