imderivgauss3_get_support.m

function [x,Wx]=imderivgauss3_get_support(sigma)
    % determine necessary filter support (for Gaussian)
    %
    % @author Boris Schauerte
    % @email  boris.schauerte@eyezag.com
    % @date   2011
    %
    % Copyright (C) 2011  Boris Schauerte
    % 
    % This program 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/>.

  %Wx = floor((5/2)*sigma * 2); % Wx = floor((5/2)*sigma); % @todo: is the support high enough? How to calculate the support for higher order derivatives? 
  %Wx = ceil(sigma*3)*2+1; % taken from matlab LoG code (http://www.mathworks.com/help/toolbox/images/ref/edge.html)
  Wx = ceil(sigma*3); % taken from matlab LoG code (http://www.mathworks.com/help/toolbox/images/ref/edge.html)
    % Note that the selected width has a measurable influence on the performance
  if Wx < 1
     Wx = 1;
  end
  x = [-Wx:Wx];