smooth.m

ICA watermarking. Blind, fragile, robust

function y=smooth(x,alfa)

[M,M]=size(x);
aux2=ones(3)*alfa;
aux2(2,2)=1;
%aux2=conv2(aux2,ones(2));
%aux2=conv2(aux2,aux2);
aux2=aux2/sum(sum(aux2));
[k1,k2]=size(aux2);
mask_smooth=zeros(M);
off=k1/2;
mask_smooth(floor(M/2-off+1+1:M/2-off+k1+1),floor(M/2+1-off+1:M/2+1-off+k1-1+1))=aux2;
mask_smooth=fftshift(mask_smooth);
dft_smooth=fft2(mask_smooth);
dft_x=fft2(x); 
y=real(ifft2(dft_x.*dft_smooth));
return