--- a
+++ b/matlab/add_dataset2.m
@@ -0,0 +1,63 @@
+function [len_M, num_false] = add_dataset2(image_file, csv_file, dataset_folder, map_file)
+
+% parameters
+% num_false = 26685;
+num_false = 26602;
+d = 10;
+d2 = d*d;
+N = 101; % must be odd
+
+R = (N-1)/2;
+
+% load image and csv files
+A = imread(image_file);
+M = csvread(csv_file);
+map = imread(map_file);
+
+[A_height, A_width, ~] = size(A);
+
+% find the centroids
+len_M = size(M,1);
+P = zeros(len_M,2);
+for i=1:len_M;
+    tmp = M(i,:);
+    tmp = tmp(tmp~=0);
+    len_tmp = size(tmp,2);
+    sum_X = 0;
+    sum_Y = 0;
+    for j=1:len_tmp/2
+        sum_X = sum_X + tmp(2*j-1);
+        sum_Y = sum_Y + tmp(2*j);
+    end
+    mean_X = 2*sum_X/len_tmp;
+    mean_Y = 2*sum_Y/len_tmp;
+    P(i,:) = [mean_Y mean_X];
+end
+M = round(P);
+
+% create negative dataset
+H = A_height - N + 1;
+W = A_width - N + 1;
+B = cell(1,num_false);
+for i=1:num_false
+    flag = true;
+    while flag
+        X = randi(W) + R;
+        Y = randi(H) + R;
+        if randi([0,255]) < map(Y,X)
+            flag = isPos(X,Y,M,d);
+        end
+    end
+    y1 = Y - R;
+    y2 = Y + R;
+    x1 = X - R;
+    x2 = X + R;
+    B{i} = A(y1:y2, x1:x2, :);
+end
+
+% write set of images to file
+n = length(dir([dataset_folder '*.png']));
+for i=1:num_false
+    file = [dataset_folder num2str(i+n,'%02u') '.png'];
+    imwrite(B{i}, file, 'png');
+end