function pick = nms(boxes, overlap, use_gpu)

% top = nms(boxes, overlap)

% Non-maximum suppression. (FAST VERSION)

% Greedily select high-scoring detections and skip detections

% that are significantly covered by a previously selected

% detection.

%

% NOTE: This is adapted from Pedro Felzenszwalb's version (nms.m),

% but an inner loop has been eliminated to significantly speed it

% up in the case of a large number of boxes

% Copyright (C) 2011-12 by Tomasz Malisiewicz

% All rights reserved.

%

% This file is part of the Exemplar-SVM library and is made

% available under the terms of the MIT license (see COPYING file).

% Project homepage: https://github.com/quantombone/exemplarsvm

if isempty(boxes)

pick = [];

return;

end

if ~exist('use_gpu', 'var')

use_gpu = false;

end

if use_gpu

s = boxes(:, end);

if ~issorted(s(end:-1:1))

[~, I] = sort(s, 'descend');

boxes = boxes(I, :);

else

I = (1:numel(s))';

end

pick = nms_gpu_mex(single(boxes)', double(overlap));

pick = I(pick);

return;

end

if size(boxes, 1) < 50000

pick = nms_mex(double(boxes), double(overlap));

return;

end

x1 = boxes(:,1);

y1 = boxes(:,2);

x2 = boxes(:,3);

y2 = boxes(:,4);

s = boxes(:,end);

area = (x2-x1+1) .* (y2-y1+1);

[vals, I] = sort(s);

pick = s*0;

counter = 1;

while ~isempty(I)

last = length(I);

i = I(last);

pick(counter) = i;

counter = counter + 1;

xx1 = max(x1(i), x1(I(1:last-1)));

yy1 = max(y1(i), y1(I(1:last-1)));

xx2 = min(x2(i), x2(I(1:last-1)));

yy2 = min(y2(i), y2(I(1:last-1)));

w = max(0.0, xx2-xx1+1);

h = max(0.0, yy2-yy1+1);

inter = w.*h;

o = inter ./ (area(i) + area(I(1:last-1)) - inter);

I = I(find(o<=overlap));

end

pick = pick(1:(counter-1));