HOW TO PERFORM ENCRYPTION AND DECRYPTION ON R,G,B COMPONENTS OF COLOUR IMAGE

a=uigetfile('*.*');

im=imread(a);

r=im(:,:,1);

g=im(:,:,2);

b=im(:,:,3);

now the carrier image which is generated by some algorithm .the carrier image is made equal to the image size.the carrier image is added to the r ,g,b compomnents and decrypt them.please help