%addpath([pwd], 'util/');
img = imread('raster_schwan.png');

for channel = 1:3
    IMG = fftshift(fft2(img(:,:,channel)));
    [sx, sy] = size(IMG);

    subplot(2, 2, channel);
    %imshow(abs(IMG) ./ max(abs(IMG)));

    sigma = 1.5;
    h = fspecial('gaussian', [sx, sy], sigma);
    H = abs(fftshift(fft2(h)));

    %H = zeros(sx, sy);
    %H = fill_circle(H, sx/2, sy/2, 30, 1);
    IMG = IMG .* H;
    imshow(abs(IMG) ./ max(abs(IMG)));

    IMG = ifftshift(IMG);
    img(:,:,channel) = uint8(real(ifft2(IMG)));
end

subplot(224);
imshow(img);