cent.m

sfrmat is a Matlab function that provides a spatial frequency response* (SFR) from a digital image f

function [b] = cent(a, center);
% [b] = cent(a, center)  Array shift for centering data
%  Matlab function cent: shift of one-dimensional
%  array, so that a(center) is located at b(round((n+1)/2).
%  Written to shift a line-spread function array prior to 
%  applying a smoothing window.
%   a      = input array
%   center = location of signal center to be shifted
%   b      = output shifted array
%  Peter Burns 5 Aug. 2002
%  Copyright (c) International Imaging Industry Association

n = length(a);
b = zeros(n, 1);
mid = round((n+1)/2);

del = round(center - mid);

if del > 0;
     for i = 1:n-del;
       b(i) = a(i + del);
     end;

elseif del < 1;
     for i = -del+1:n;
       b(i) = a(i + del);
     end;

   else b = a;
end;