opencv/samples/cpp/imagelist_reader.cpp

/*
 *  Created on: Nov 23, 2010
 *      Author: Ethan Rublee
 *
 * A starter sample for using opencv, load up an imagelist
 * that was generated with imagelist_creator.cpp
 * easy as CV_PI right?
 */
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include <iostream>
#include <vector>

using namespace cv;
using namespace std;

static void help(char** av)
{
  cout << "\nThis program gets you started being able to read images from a list in a file\n"
          "Usage:\n./" << av[0] << " image_list.yaml\n"
       << "\tThis is a starter sample, to get you up and going in a copy pasta fashion.\n"
       << "\tThe program reads in an list of images from a yaml or xml file and displays\n"
       << "one at a time\n"
       << "\tTry running imagelist_creator to generate a list of images.\n"
        "Using OpenCV version %s\n" << CV_VERSION << "\n" << endl;
}

static bool readStringList(const string& filename, vector<string>& l)
{
  l.resize(0);
  FileStorage fs(filename, FileStorage::READ);
  if (!fs.isOpened())
    return false;
  FileNode n = fs.getFirstTopLevelNode();
  if (n.type() != FileNode::SEQ)
    return false;
  FileNodeIterator it = n.begin(), it_end = n.end();
  for (; it != it_end; ++it)
    l.push_back((string)*it);
  return true;
}

static int process(const vector<string>& images)
{
    namedWindow("image", WINDOW_KEEPRATIO); //resizable window;
    for (size_t i = 0; i < images.size(); i++)
    {
        Mat image = imread(images[i], IMREAD_GRAYSCALE); // do grayscale processing?
        imshow("image",image);
        cout << "Press a key to see the next image in the list." << endl;
        waitKey(); // wait infinitely for a key to be pressed
    }
    return 0;
}

int main(int ac, char** av)
{
  cv::CommandLineParser parser(ac, av, "{help h||}{@input||}");
  if (parser.has("help"))
  {
      help(av);
      return 0;
  }
  std::string arg = parser.get<std::string>("@input");
  if (arg.empty())
  {
    help(av);
    return 1;
  }
  vector<string> imagelist;

  if (!readStringList(arg,imagelist))
  {
    cerr << "Failed to read image list\n" << endl;
    help(av);
    return 1;
  }

  return process(imagelist);
}