fast_tree_to_matlab_score_bsearch

#!/usr/bin/env bash
#    This file is part of the FAST-ER machine learning system.
#    Copyright (C) 2008  Edward Rosten and Los Alamos National Laboratory
#
#    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 2 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, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

file="$2"
name="$1"
if [ "$#" != 2 ]
then
	echo `basename $0`: error: incorrect arguments.
	echo "Usage:  `basename $0` <function_name> <file>"
	exit 1
fi

debug_use_test_rig=0

num_offsets=$(head -1 $file)


border=$(
      awk '
        NR==1{features = $1}
        NR==2{
          gsub(/[\[\],]/, "")
          if(features != NF/2)
          {
            print "Malformed offsets line"
            exit(1);
          }
		  o=0
          
          for(x=1; x <= NF; x++)
		  	o = ($x > o? $x : o)

		  print o

		  exit(0);
      } ' $file 
)



if [ "$debug_use_test_rig" == 1 ]
then
cat<<END

function test()
	image = imread('frame_1.pgm');
	
	corners = ${name}(image, 20, 'nonmax');

	imshow(image);
	hold on
	plot(corners(:,1), corners(:,2), 'r.')

END
fi


uppername=$(echo $name | tr '[a-z]' '[A-Z]')

cat << END
%$uppername perform an  FAST corner detection from your FAST-ER generated tree
%    [corners, scores] = $uppername(image, threshold) performs the detection on the image
%    and returns the X coordinates in corners(:,1), the Y coordinares in corners(:,2) and
%    optionally, the scores in scores(:). The score is computed using binary search over 
%    all possible thresholds.
%
%    [corners, scores] = $uppername(image, threshold, nonmax) performs the corner
%    detection and nonmaximal suppression if nonmax is not zero. 
%    
%     If you use this in published work, please cite:
%       Faster and better: A machine learning approach to corner detection, E. Rosten, R. Porter and T. Drummond, PAMI (to appear) 2008
%       Machine learning for high-speed corner detection, E. Rosten and T. Drummond, ECCV 2006
%     The Bibtex entries are:
%     
%     @inproceedings{rosten_2006_machine,
%         title       =    "Machine learning for high-speed corner detection",
%         author      =    "Edward Rosten and Tom Drummond",
%         year        =    "2006",
%         month       =    "May",
%         booktitle   =    "European Conference on Computer Vision (to appear)",
%         notes       =    "Poster presentation",
%         url         =    "http://mi.eng.cam.ac.uk/~er258/work/rosten_2006_machine.pdf"
%     }
%
%     @article{rosten_2008_faster,
%         title       =    "Faster and better: A machine learning approach to corner detection",
%         author      =    "Edward Rosten and Reid Porter and Tom Drummond",
%         year        =    "2008",
%         month       =    "October",
%         journal     =    "IEEE Transactions on Pattern Analysis and Machine Intelligence (to appear)",
%         eprint      =    "arXiv:0810.2434 [cs.CV]",
%         url         =    "http://lanl.arXiv.org/pdf/0810.2434"
%     }
function [ corners scores ] = ${name}(image, threshold, do_nonmax)
	
	corners = zeros(1024, 2);
	num_corners=0;

	for y=$((border+1)):size(image,1)-$((border+1))
		
		for x=$((border+1)):size(image,2)-$((border+1))
			cb = image(y, x) + threshold;
			c_b = image(y, x) - threshold;
$(
		awk '
			NR==1{features = $1}
			NR==2{
				gsub(/[\[\],]/, "")
				for(x=1; x <= features; x++)
				{
					offx[x-1] = $(2*x-1)
					offy[x-1] = $(2*x)
				}
			}

			{ ind = "          "substr($0, 1, match($0, /[^ ]/)-1)}

			{ accessor = "image(y+"offy[$2]",x+"offx[$2]")" }

			/if_brighter/{print ind "if " accessor " > cb "}

			/elsf_darker/ {print ind "elseif " accessor " < c_b "}
			/if_darker/{print ind "if " accessor " < c_b"}
			/if_either/{print ind "if " accessor " > cb | " accessor " < c_b "}
			/else/{print ind "else"}
			/end/{print ind "end"}
			/background/{print ind "continue"}
				' $file
			)




				
			num_corners = num_corners + 1;
			corners(num_corners, 1) = x;
			corners(num_corners, 2) = y;
			
			if num_corners == length(corners)
				corners(end*2,1)=0;
			end
		end
	end

	corners = corners(1:num_corners, :);

	if ~exist('do_nonmax')
		do_nonmax=0;
	end
		
	if nargout == 2 | do_nonmax

		scores = zeros(num_corners, 1);

		for i=1:num_corners
			scores(i) = corner_score(image, corners(i, 1), corners(i, 2));
		end
	end

	if do_nonmax
		rows = size(image, 1);
		offsets = [ rows+1 rows rows-1 1 -1 -rows+1 -rows -rows-1];

	
		rcorners=zeros(size(corners));
		rscores=zeros(size(scores));
		num_nonmax=0;
	
		score_image = -ones(size(image));

		score_image(sub2ind(size(image), corners(:,2), corners(:,1))) = scores;

		for i=1:num_corners
			pos = sub2ind(size(image), corners(i,2), corners(i, 1));

			if all(score_image(pos) > score_image(pos + offsets))
				num_nonmax = num_nonmax+1;
				rcorners(num_nonmax,:) = corners(i,:);
				rscores(num_nonmax) = scores(i);
			end
		end

		corners = rcorners(1:num_nonmax, :);
		scores = rscores(1:num_nonmax);




	end

function c = is_a_corner(i, posx, posy, b)
	cb = i(posy, posx) + b;
	c_b = i(posy, posx) - b;
$(
	awk '
		NR==1{features = $1}
		NR==2{
        	gsub(/[\[\],]/, "")
			for(x=1; x <= features; x++)
			{
				offx[x-1] = $(2*x-1)
				offy[x-1] = $(2*x)
			}
		}

		{ ind = "        "substr($0, 1, match($0, /[^ ]/)-1)}

		{ accessor = "i(posy+"offy[$2]",posx+"offx[$2]")" }

		/if_brighter/{print ind "if " accessor " > cb "}

		/elsf_darker/ {print ind "elseif " accessor " < c_b "}
		/if_darker/{print ind "if " accessor " < c_b"}
		/if_either/{print ind "if " accessor " > cb | " accessor " < c_b "}
		/else/{print ind "else"}
		/end/{print ind "end"}
		/corner/{print ind "c=1; return"}
		/background/{print ind "c=0; return"}
            ' $file
        )

function bmin = corner_score(i, posx, posy)
    
    bmin = 0;
    bmax = 255;
    b = floor((bmax + bmin)/2);
    
    %Compute the score using binary search
	while 1
    
		if(is_a_corner(i, posx, posy, b))
           	bmin = b;
		else
            bmax = b;
		end
        
		if bmin == bmax - 1 | bmin == bmax 
			return
		end
		b = floor(bmin + bmax) / 2;
    end


END