loadimg

  cv::Mat opencv_mat = cv::imread(files[0], CV_LOAD_IMAGE_COLOR);   // Read the file
  opencv_mat.convertTo(opencv_mat, CV_64FC3);
  arma::mat dataset(opencv_mat.ptr<double>(), 1, opencv_mat.rows * opencv_mat.cols * 3);

  size_t N_IMAGES = files.size()-1;
  for(size_t i = 1;i < N_IMAGES; i++){
    cv::Mat opencv_mat = cv::imread(files[i], CV_LOAD_IMAGE_COLOR);   // Read the file
    opencv_mat.convertTo(opencv_mat, CV_64FC3);

    arma::mat arma_mat(opencv_mat.ptr<double>(), 1, opencv_mat.rows * opencv_mat.cols * 3);
    dataset = join_cols(dataset, arma_mat);
  }