discrete_fourier_transform_nodelet.cpp

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// https://github.com/opencv/opencv/blob/2.4/samples/cpp/tutorial_code/core/discrete_fourier_transform/discrete_fourier_transform.cpp
#include <image_transport/image_transport.h>
#include <sensor_msgs/image_encodings.h>
#include <cv_bridge/cv_bridge.h>
#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

#include "opencv_apps/nodelet.h"
#include "opencv_apps/DiscreteFourierTransformConfig.h"

#include <dynamic_reconfigure/server.h>

namespace discrete_fourier_transform {
class DiscreteFourierTransformNodelet : public opencv_apps::Nodelet {
  image_transport::Publisher img_pub_;
  image_transport::Subscriber img_sub_;
  image_transport::CameraSubscriber cam_sub_;

  boost::shared_ptr<image_transport::ImageTransport> it_;

  typedef discrete_fourier_transform::DiscreteFourierTransformConfig Config;
  typedef dynamic_reconfigure::Server<Config> ReconfigureServer;
  Config config_;
  boost::shared_ptr<ReconfigureServer> reconfigure_server_;

  bool debug_view_;
  ros::Time prev_stamp_;

  boost::mutex mutex_;

  std::string window_name_;

  void imageCallbackWithInfo(
                             const sensor_msgs::ImageConstPtr& msg,
                             const sensor_msgs::CameraInfoConstPtr& cam_info) {
    do_work(msg, cam_info->header.frame_id);
  }

  void imageCallback(const sensor_msgs::ImageConstPtr& msg) {
    do_work(msg, msg->header.frame_id);
  }

  void subscribe() {
    NODELET_DEBUG("Subscribing to image topic.");
    if (config_.use_camera_info)
      cam_sub_ = it_->subscribeCamera(
                                      "image", 1, &DiscreteFourierTransformNodelet::imageCallbackWithInfo, this);
    else
      img_sub_ =
        it_->subscribe("image", 1, &DiscreteFourierTransformNodelet::imageCallback, this);
  }

  void unsubscribe() {
    NODELET_DEBUG("Unsubscribing from image topic.");
    img_sub_.shutdown();
    cam_sub_.shutdown();
  }

  void reconfigureCallback(Config& config, uint32_t level) {
    boost::mutex::scoped_lock lock(mutex_);
    config_ = config;
  }

  void do_work(const sensor_msgs::Image::ConstPtr& image_msg,
               const std::string input_frame_from_msg) {
    // Work on the image.
    try {
        cv::Mat src_image =
          cv_bridge::toCvShare(image_msg, image_msg->encoding)->image;
        if(src_image.channels() > 1) {
          cv::cvtColor(src_image, src_image, CV_BGR2GRAY);
        }

        cv::Mat padded;                            //expand input image to optimal size
        int m = cv::getOptimalDFTSize(src_image.rows);
        int n = cv::getOptimalDFTSize(src_image.cols); // on the border add zero values
        cv::copyMakeBorder(src_image, padded, 0, m - src_image.rows, 0, n - src_image.cols, cv::BORDER_CONSTANT, cv::Scalar::all(0));

        cv::Mat planes[] = {cv::Mat_<float>(padded), cv::Mat::zeros(padded.size(), CV_32F)};
        cv::Mat complex_image;
        cv::merge(planes, 2, complex_image);         // Add to the expanded another plane with zeros
        cv::dft(complex_image, complex_image);            // this way the result may fit in the source matrix

        // compute the magnitude and switch to logarithmic scale
        // => log(1 + sqrt(Re(DFT(I))^2 + Im(DFT(I))^2))
        cv::split(complex_image, planes);                   // planes[0] = Re(DFT(I), planes[1] = Im(DFT(I))
        cv::magnitude(planes[0], planes[1], planes[0]);// planes[0] = magnitude
        cv::Mat magnitude_image = planes[0];
        magnitude_image += cv::Scalar::all(1);                    // switch to logarithmic scale
        cv::log(magnitude_image, magnitude_image);

        // crop the spectrum, if it has an odd number of rows or columns
        magnitude_image = magnitude_image(cv::Rect(0, 0, magnitude_image.cols & -2, magnitude_image.rows & -2));
        // rearrange the quadrants of Fourier imagev  so that the origin is at the image center
        int cx = magnitude_image.cols / 2;
        int cy = magnitude_image.rows / 2;

        cv::Mat q0(magnitude_image, cv::Rect(0, 0, cx, cy));   // Top-Left - Create a ROI per quadrant
        cv::Mat q1(magnitude_image, cv::Rect(cx, 0, cx, cy));  // Top-Right
        cv::Mat q2(magnitude_image, cv::Rect(0, cy, cx, cy));  // Bottom-Left
        cv::Mat q3(magnitude_image, cv::Rect(cx, cy, cx, cy)); // Bottom-Right

        cv::Mat tmp;                           // swap quadrants (Top-Left with Bottom-Right)
        q0.copyTo(tmp);
        q3.copyTo(q0);
        tmp.copyTo(q3);

        q1.copyTo(tmp);                    // swap quadrant (Top-Right with Bottom-Left)
        q2.copyTo(q1);
        tmp.copyTo(q2);
        cv::normalize(magnitude_image, magnitude_image, 0, 255, cv::NORM_MINMAX);

        cv::Mat result_image = cv::Mat::zeros(magnitude_image.rows, magnitude_image.cols, CV_8UC1);
        for(int i=0;i<magnitude_image.rows;++i) {
          unsigned char* result_data = result_image.ptr<unsigned char>(i);
          float* magnitude_data = magnitude_image.ptr<float>(i);
          for(int j=0;j<magnitude_image.cols;++j) {
            *result_data++ = (unsigned char)(*magnitude_data++);
          }
        }

        if( debug_view_) {
          cv::imshow( window_name_, result_image );
          int c = cv::waitKey(1);
        }
        img_pub_.publish(cv_bridge::CvImage(image_msg->header,
                                            sensor_msgs::image_encodings::MONO8,
                                            result_image).toImageMsg());
    }
    catch (cv::Exception &e) {
      NODELET_ERROR("Image processing error: %s %s %s %i", e.err.c_str(), e.func.c_str(), e.file.c_str(), e.line);
    }

    prev_stamp_ = image_msg->header.stamp;
  }

public:
  virtual void onInit() {
    Nodelet::onInit();
    it_ = boost::shared_ptr<image_transport::ImageTransport>(new image_transport::ImageTransport(*nh_));
    pnh_->param("debug_view", debug_view_, false);

    if (debug_view_) {
      always_subscribe_ = true;
    }
    prev_stamp_ = ros::Time(0, 0);

    window_name_ = "Discrete Fourier Transform Demo";

    reconfigure_server_ = boost::make_shared<dynamic_reconfigure::Server<Config> >(*pnh_);
    dynamic_reconfigure::Server<Config>::CallbackType f =
      boost::bind(&DiscreteFourierTransformNodelet::reconfigureCallback, this, _1, _2);
    reconfigure_server_->setCallback(f);

    img_pub_ = advertiseImage(*pnh_, "image", 1);
    onInitPostProcess();
  }
};
}

#include <pluginlib/class_list_macros.h>
PLUGINLIB_EXPORT_CLASS(discrete_fourier_transform::DiscreteFourierTransformNodelet, nodelet::Nodelet);