--- /dev/null
+/*
+ * mlp-mnist is an implementation of a multi-layer neural network.
+ *
+ * Copyright (c) 2008 Idiap Research Institute, http://www.idiap.ch/
+ * Written by Francois Fleuret <francois.fleuret@idiap.ch>
+ *
+ * This file is part of mlp-mnist.
+ *
+ * mlp-mnist is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * mlp-mnist 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 mlp-mnist. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "images.h"
+#include <stdlib.h>
+
+PixelMaps::PixelMaps(int size) : _nb_ref(0),_core(new unsigned char[size]) {}
+PixelMaps::~PixelMaps() { delete[] _core; }
+PixelMaps *PixelMaps::add_ref() { _nb_ref++; return this; }
+void PixelMaps::del_ref() { _nb_ref--; if(_nb_ref == 0) delete this; }
+
+const unsigned int mnist_pictures_magic = 0x00000803;
+const unsigned int mnist_labels_magic = 0x00000801;
+
+inline unsigned int read_high_endian_int(istream &is) {
+ unsigned int result;
+ char *s = (char *) &result;
+ char c;
+ is.read(s, sizeof(result));
+ c = s[0]; s[0] = s[3]; s[3] = c;
+ c = s[1]; s[1] = s[2]; s[2] = c;
+ return result;
+}
+
+ImageSet::ImageSet() : _nb_pics(-1), _nb_obj(0), _width(-1), _height(-1),
+ _pixel_maps(0), _pixels(0), _labels(0), _used_picture(0) { }
+
+ImageSet::~ImageSet() {
+ if(_pixel_maps) _pixel_maps->del_ref();
+ delete[] _pixels;
+ delete[] _labels;
+ delete[] _used_picture;
+}
+
+void ImageSet::reset_used_pictures() {
+ for(int p = 0; p < _nb_pics; p++) _used_picture[p] = false;
+}
+
+int ImageSet::nb_unused_pictures() {
+ int n = 0;
+ for(int p = 0; p < _nb_pics; p++) if(!_used_picture[p]) n++;
+ return n;
+}
+
+int ImageSet::pick_unused_picture() {
+ int m;
+ do { m = int(drand48() * _nb_pics); } while(_used_picture[m]);
+ _used_picture[m] = true;
+ return m;
+}
+
+void ImageSet::extract_unused_pictures(ImageSet &is, int nb) {
+ if(nb > is.nb_unused_pictures()) {
+ cerr << "Trying to extract " << nb << " pictures from a set of " << is.nb_unused_pictures() << "\n";
+ exit(1);
+ }
+
+ _nb_pics = nb;
+ _width = is._width;
+ _height = is._height;
+ _nb_obj = is._nb_obj;
+ _pixel_maps = is._pixel_maps->add_ref();
+ _pixels = new unsigned char *[_nb_pics];
+ _labels = new unsigned char[_nb_pics];
+ _used_picture = new bool[_nb_pics];
+ for(int n = 0; n < _nb_pics; n++) {
+ int m = is.pick_unused_picture();
+ _pixels[n] = is._pixels[m];
+ _labels[n] = is._labels[m];
+ }
+
+ reset_used_pictures();
+}
+
+void ImageSet::load_mnist_format(char *picture_file_name, char *label_file_name) {
+ unsigned int magic;
+
+ ifstream picture_is(picture_file_name);
+
+ if(picture_is.fail()) {
+ cerr << "Can not open file [" << picture_file_name << "].\n";
+ exit(1);
+ }
+
+ magic = read_high_endian_int(picture_is);
+ if(magic != mnist_pictures_magic) {
+ cerr << "Invalid magic for picture, file [" << picture_file_name << "] number [" << magic << "]\n";
+ exit(1);
+ }
+
+ _nb_pics = read_high_endian_int(picture_is);
+ _width = read_high_endian_int(picture_is);
+ _height = read_high_endian_int(picture_is);
+
+ ifstream label_is(label_file_name);
+ if(label_is.fail()) {
+ cerr << "Can not open file [" << label_file_name << "].\n";
+ exit(1);
+ }
+
+ magic = read_high_endian_int(label_is);
+ if(magic != mnist_labels_magic) {
+ cerr << "Invalid magic for labels, file [" << label_file_name << "] number [" << magic << "]\n";
+ exit(1);
+ }
+
+ int nb_pics_labels = read_high_endian_int(label_is);
+
+ if(nb_pics_labels != _nb_pics) {
+ cerr << "Inconsistency between the number of pictures in [" << picture_file_name << "] (" << _nb_pics << ")"
+ << " and the number of labels in [" << label_file_name << "] (" << nb_pics_labels << ").\n";
+ exit(1);
+ }
+
+ PixelMaps *pm = new PixelMaps(_nb_pics * _width * _height);
+ _pixel_maps = pm->add_ref();
+ _pixels = new unsigned char *[_nb_pics];
+ _labels = new unsigned char[_nb_pics];
+ _used_picture = new bool[_nb_pics];
+
+ picture_is.read((char *) _pixel_maps->_core, _nb_pics * _width * _height);
+ label_is.read((char *) _labels, _nb_pics);
+
+ for(int i = 0; i < _nb_pics * _width * _height; i++) _pixel_maps->_core[i] = 255 - _pixel_maps->_core[i];
+
+ _nb_obj = 0;
+ for(int n = 0; n < _nb_pics; n++) {
+ _pixels[n] = _pixel_maps->_core + n * _width * _height;
+ if(_labels[n] > _nb_obj) _nb_obj = _labels[n];
+ }
+ _nb_obj++;
+
+ reset_used_pictures();
+}