MATLAB: How I can insert a simple message on a picture ?

Question

%this is the code to create a watermark image with key :

clc;clear all;close all;

img = imread('C:\Users\yassine\Desktop\wmark\home.jpg');

img = rgb2gray(img);

img = double(img);

c = 0.01; %Initialise the weight of Watermarking

figure,imshow(uint8(img)),title('Original Image');

[p q] = size(img);

%Generate the key

n = awgn(img,4,3,'linear');

N = imabsdiff(n,img);

figure,imshow(double(N)),title('Key');

[Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('haar');

[ca,ch,cv,cd] = dwt2(img,Lo_D,Hi_D);

%Perform the watermarking

y = [ca ch;cv cd]; Y = y + c*abs(y).* N;

p=p/2;q=q/2; for i=1:p for j=1:q nca(i,j) = Y(i,j); ncv(i,j) = Y(i+p,j); nch(i,j) = Y(i,j+q); ncd(i,j) = Y (i+p,j+q); end end

wimg = idwt2(nca,nch,ncv,ncd,Lo_R,Hi_R);

figure,imshow(uint8(wimg)),title('Watermarked Image');

diff = imabsdiff(wimg,img);

figure,imshow(double(diff));title('Differences');

%but the key is used to protect the message so how I can insert my own msg(HELLO) in the image (regardless spatial domain or frequentiel)

Answer 1

Attached is my watermarking demo. It's sort of hidden watermarking - a primitive form of steganography. Do you require your message to be hidden or encrypted?