Function main

tools/compute_image_mean.cpp:24–125

        "The backend {leveldb, lmdb} containing the images");

int main(int argc, char** argv) {
#ifdef USE_OPENCV
  ::google::InitGoogleLogging(argv[0]);
  // Print output to stderr (while still logging)
  FLAGS_alsologtostderr = 1;

#ifndef GFLAGS_GFLAGS_H_
  namespace gflags = google;
#endif

  gflags::SetUsageMessage("Compute the mean_image of a set of images given by"
        " a leveldb/lmdb\n"
        "Usage:\n"
        "    compute_image_mean [FLAGS] INPUT_DB [OUTPUT_FILE]\n");

  gflags::ParseCommandLineFlags(&argc, &argv, true);

  if (argc < 2 || argc > 3) {
    gflags::ShowUsageWithFlagsRestrict(argv[0], "tools/compute_image_mean");
    return 1;
  }

  scoped_ptr<db::DB> db(db::GetDB(FLAGS_backend));
  db->Open(argv[1], db::READ);
  scoped_ptr<db::Cursor> cursor(db->NewCursor());

  BlobProto sum_blob;
  int count = 0;
  // load first datum
  Datum datum;
  datum.ParseFromString(cursor->value());

  if (DecodeDatumNative(&datum)) {
    LOG(INFO) << "Decoding Datum";
  }

  sum_blob.set_num(1);
  sum_blob.set_channels(datum.channels());
  sum_blob.set_height(datum.height());
  sum_blob.set_width(datum.width());
  const int data_size = datum.channels() * datum.height() * datum.width();
  int size_in_datum = std::max<int>(datum.data().size(),
                                    datum.float_data_size());
  for (int i = 0; i < size_in_datum; ++i) {
    sum_blob.add_data(0.);
  }
  LOG(INFO) << "Starting iteration";
  while (cursor->valid()) {
    Datum datum;
    datum.ParseFromString(cursor->value());
    DecodeDatumNative(&datum);

    const std::string& data = datum.data();
    size_in_datum = std::max<int>(datum.data().size(),
        datum.float_data_size());
    CHECK_EQ(size_in_datum, data_size) << "Incorrect data field size " <<
        size_in_datum;
    if (data.size() != 0) {