Matlab_WHOGeneric/misc/nonMaxSupp.m

function [top, pick] = nonMaxSupp(boxes,overlap,numpart)
% Non-maximum suppression.
% Greedily select high-scoring detections and skip detections
% that are significantly covered by a previously selected detection.
pick=[];
if nargin < 2
    overlap = 0.5;
end
if nargin < 3
    numpart = floor(size(boxes,2)/4);
end

if isempty(boxes)
  top = [];
else
  x1 = zeros(size(boxes,1),numpart);
  y1 = zeros(size(boxes,1),numpart);
  x2 = zeros(size(boxes,1),numpart);
  y2 = zeros(size(boxes,1),numpart);
  area = zeros(size(boxes,1),numpart);
  for p = 1:numpart
    x1(:,p) = boxes(:,1+(p-1)*4);
    y1(:,p) = boxes(:,2+(p-1)*4);
    x2(:,p) = boxes(:,3+(p-1)*4);
    y2(:,p) = boxes(:,4+(p-1)*4);
    area(:,p) = (x2(:,p)-x1(:,p)+1) .* (y2(:,p)-y1(:,p)+1);
  end
  
  s = boxes(:,5);
  [vals, I] = sort(s);
  pick = [];
  while ~isempty(I)
	
    last = length(I);
    i = I(last);
	%similar=find(abs(s(I)-s(i))<1e-5);
	%[m,i]=max(area(I(similar)));
	%i=I(similar(i));
	%disp('here');
	
	%pause;
    pick = [pick; i];

    xx1 = bsxfun(@max,x1(i,:), x1(I,:));
    yy1 = bsxfun(@max,y1(i,:), y1(I,:));
    xx2 = bsxfun(@min,x2(i,:), x2(I,:));
    yy2 = bsxfun(@min,y2(i,:), y2(I,:));
    
    w = xx2-xx1+1;
    w(w<0) = 0;
    h = yy2-yy1+1;
    h(h<0) = 0;    
    inter  = sum(w.*h,2);
    o = double(inter) ./double(sum(area(I,:),2));
    I(o > overlap) = [];
	
  end  
  top = boxes(pick,:);
end