function [out, vmax] = psf(inp, vref);
% PSF
%
%     [out, vmax] = psf(inp) generates the normalized point spread function
%
% inp   input image
% out   output image (normalized to unity)
% vmax  normalization parameter
%
%     [out, vmax] = psf(inp,vref) uses vref to normalize the output.
%     vmax is then the ratio of the maximum value to the reference value.

%  Author:  John S. Loomis  (15 March 2000)

f = fft2(inp);
f = fftshift(f);
out = f.*conj(f);
vmax = max(out(:));
if (nargin>1)
   out = out/vref;
   vmax = vmax/vref;
else
   out = out/vmax;
end

Published with MATLAB® 7.6