filt_get_s2b_nn1999.m

Standard model object recognition matlab code

function [f1, f2, shift] = filt_get_S2b_NN1999

% FUNCTION [f1, f2, shift] = filt_get_S2b_NN1999
%
% This function creates the S2b filters based on the original "HMAX"
% S2b convention that appeared in 1999 Nature Neuroscience
% (Riesenhuber and Poggio).  Namely, each S2b unit pools from 2x2
% grid of C1 units.

num_orientation = 4;
num_scale_bands = 4;
num_old_feature = num_orientation;
num_new_feature = 256;

% Overlap of 2, and we want to take adjacent C1's.
f = zeros(3,3,num_old_feature,num_new_feature);
idx = 0;
for i = [1:num_orientation]
  for j = [1:num_orientation]
    for k = [1:num_orientation]
      for l = [1:num_orientation]
	idx = idx+1;
	f(1,1,i,idx) = 1;
	f(1,3,j,idx) = 1;
	f(3,1,k,idx) = 1;
	f(3,3,l,idx) = 1;
      end
    end
  end
end

f1 = f;
f2 = f;
shift = 1;

% Save in the packaged format.
f = [];
f = filt_package(f,f1,f2,shift,'s1');
save f_S2b_NN1999 f;