windowmask.m

function [W]=windowmask(N,R)
% --- Gaussian Window Mask Subfunction ---
% JJC: 2014-08-15 - This has a small bug, I think.  Because the WIDTH of
% the window is actually N-1 (for N grid points), the expressions for px
% and py need to be changed to use N-1, not N.  x and y are correct.  R
% doesn't change since it should be a width already, not a count of grid
% points.

%     This file is part of prana, an open-source GUI-driven program for
%     calculating velocity fields using PIV or PTV.
%     Copyright (C) 2012  Virginia Polytechnic Institute and State
%     University
% 
%     prana is free software: you can redistribute it and/or modify
%     it under the terms of the GNU General Public License as published by
%     the Free Software Foundation, either version 3 of the License, or
%     (at your option) any later version.
% 
%     This program is distributed in the hope that it will be useful,
%     but WITHOUT ANY WARRANTY; without even the implied warranty of
%     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%     GNU General Public License for more details.
% 
%     You should have received a copy of the GNU General Public License
%     along with this program.  If not, see <http://www.gnu.org/licenses/>.


% %generic indices
x  = -1:2/(N(1)-1):1;
y  = (-1:2/(N(2)-1):1)';
% 
% %gaussian window sizes
% px = (1.224*N(1)/R(1))^1.0172;
% py = (1.224*N(2)/R(2))^1.0172;
[px]=findwidth(R(1)/N(1));
[py]=findwidth(R(2)/N(2));
% 
% %generate 2D window
wx=exp(-px^2.*x.^2/2);
wy=exp(-py^2.*y.^2/2);

W  = wy*wx;

end