问使用dwt和dct分解和重新组合图像。

EN

final_image = idwt2( idct2 ( dct2 ( dwt2 (starting_image))))

clear all; clc;

%   read lena img
lena = double(imread('lena.jpg'));

%   read watermark img
%w = imread('mark.png');
load cookiebears.mat

%   compure DWT on lena and watermark
[approximate_lena, horizontal_lena, vertical_lena, diagonal_lena] = dwt2(lena, 'haar');

%   i have to save the image first and then open it in order to use it in
%   dct2() omitting this step generate an error
imwrite(uint8(approximate_lena), 'ca_lena.jpg');

%   read approximate_lena layer in a variable
lena_ca = double(imread('ca_lena.jpg'));

%   perform DCT on approximation level of lena picture
dct_lena = dct2(lena_ca);

%   embed the watermark into dct_lena
%   insert here function to embed the watermark
%   dct_lena = insert_watermark();

%   now I can recompose the lena coefficients approximation 
lena_ca_recomposed = idct2(dct_lena);

%   recompose DWT
lena_recomposed = idwt2(lena_ca_recomposed, horizontal_lena,vertical_lena, diagonal_lena, 'haar');