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Fixed wrap around effect in antonioGaussian #9

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Fixed wrap around effect in antonioGaussian #9

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7e4aac4
Fixed wrap around effect in antonioGaussian
dberga Jan 20, 2017
42ababa
Update antonioGaussian.m
dberga Feb 1, 2017
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38 changes: 31 additions & 7 deletions code_forMetrics/antonioGaussian.m
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
function [BF, gf]=gaussian(img, fc)
function [BF, gf]=antonioGaussian(img, fc)
% Gaussian low pass filter (with circular boundary conditions).
%
% [BF, gf]=gaussian(img, fc);
Expand All @@ -24,32 +24,42 @@
% due to zero padding of the input.

% Antonio Torralba, 1999
% edited: David Berga, Jan 2017

[sn, sm, c]=size(img);
n=max([sn sm]);
n=n+mod(n,2);
n = 2^ceil(log2(n));

img2 = zeropadimage(img,n); %image with zero padding
[sn2, sm2, c2]=size(img2);
n2=max([sn2 sm2]);
%n2=n2+mod(n2,2);
%n2 = 2^ceil(log2(n2));

% frequencies:
[fx,fy]=meshgrid(0:n-1,0:n-1);
fx=fx-n/2; fy=fy-n/2;

% convert cut of frequency into gaussian width:
s=fc/sqrt(log(2));
s=round(n2/n) * fc/sqrt(log(2)); %re-scaled to padded image dimensions

% compute transfer function of gaussian filter:
gf=exp(-(fx.^2+fy.^2)/(s^2));
gf = fftshift(gf);

gf2 = zeros(n2,n2,c); gf2(n2/2-n/2+1:n2/2+n/2,n2/2-n/2+1:n2/2+n/2,:) = gf;
gf2 = fftshift(gf2);


% convolve (in Fourier domain) each color band:
BF = zeros(n,n,c);
BF = zeros(n2,n2,c);
for i = 1:c
BF(:,:,i)=real(ifft2(fft2(img(:,:,i),n,n).*gf));
%BF(:,:,i)=real(ifft2(fftshift(fftshift(fft2(img(:,:,i),n,n)).*gf)));
BF(:,:,i)=real(ifft2(fft2(img2(:,:,i),n2,n2).*gf2));
%BF(:,:,i)=real(ifft2(fftshift(fftshift(fft2(img2(:,:,i),n2,n2)).*gf2)));
end

% crop output to have same size than the input
BF=BF(1:sn,1:sm,:);
BF=BF(n+1:n+sn,n+1:n+sm,:);

% if no input parameters are provided, then it shows a section of the
% gaussian filter:
Expand All @@ -63,5 +73,19 @@
xlabel('cycles per image')
ylabel('amplitude transfer function')
end
end


function [Ipad] = zeropadimage(I,p)

%Find size of image
[h, w] = size(I);

%Pad edges
Ipad = zeros(2*p, 2*p);

%Middle
Ipad(p+1:p+h, p+1:p+w) = I;

end