distortion_maps/main.cpp

Shows how a distortion map can be used to undistort an image to be pinhole-like.

// Read lens distortion maps and use them to undistort a new camera image.
//
// (c) Calib.io ApS
 
#include <opencv2/opencv.hpp>
 
bool readCalibDistortionMap(const std::string &filePathBase, cv::Matx33d &K,
                            cv::Mat_<float> &mapU, cv::Mat_<float> &mapV) {
 
  cv::FileStorage fs(filePathBase + "_K.json", cv::FileStorage::READ);
 
  try {
    fs["K"] >> K;
  } catch (...) {
    return false;
  }
  mapU = cv::imread(filePathBase + "_mapU.exr", cv::IMREAD_UNCHANGED);
  mapV = cv::imread(filePathBase + "_mapV.exr", cv::IMREAD_UNCHANGED);
 
  return true;
}
 
int main(int argc, char *argv[]) {
 
  const cv::String keys =
      "{help h usage ?       |      | print this message}"
      "{@distortionPathBase  |<none>| common part of mapU, mapV and K files}"
      "{@imagePath           |<none>| the camera image to be undistorted}";
 
  cv::CommandLineParser parser(argc, argv, keys);
 
  std::string distortionPathBase = parser.get<std::string>(0);
  std::string imagePath = parser.get<std::string>(1);
 
  if (parser.has("help") || !parser.check()) {
    parser.printMessage();
    return 0;
  }
 
  cv::Matx33d K;
  cv::Mat_<float> mapU, mapV;
  readCalibDistortionMap(distortionPathBase, K, mapU, mapV);
 
  cv::Mat im = cv::imread(imagePath);
  cv::Mat imUndistorted;
  cv::remap(im, imUndistorted, mapU, mapV, cv::INTER_CUBIC);
 
  cv::imshow("im", im);
  cv::imshow("imUndistorted", imUndistorted);
  cv::waitKey(0);
 
  return 0;
}