%% filtr butterwortha, dolnoprzepustowy.
a = imread('cameraman.tif');
a = double(a)/255; %konwersja do doubli
A = fftshift(fft2(a)); % transformata
WA = abs(A);
maska = zeros(size(a));
maska(128,128) = 1;
maska = bwdist(maska,'euclidean');
N = 8;
r = [5 10 20 50 100];
for k=1:5
%1/(1+(f/f0)^(2n))
LP = 1.0./(1+(maska/r(k)).^(2*N));
B=A.*LP;
a_new=ifft2(ifftshift(B));
subplot(2,3,k); imshow(a_new);
title(['r = ', int2str(r(k)), 'px']);
end
subplot(236), imshow(a_new);