Python OpenCV C++ Wrapper (SWIG)

makefile

all:
	swig -c++ -python opencv_facedetect.i
	g++ -Wall -fPIC -c opencv_facedetect.cpp `pkg-config --cflags opencv`
	g++ -Wall -fPIC -c opencv_facedetect_wrap.cxx `pkg-config --cflags python`
	g++ -shared opencv_facedetect.o opencv_facedetect_wrap.o `pkg-config --libs opencv` `pkg-config --libs python` -o _opencv_facedetect.so

clean:
	rm -f ./*.o $(PROG)

opencv_facedetect.cpp

#include <iostream>
#include <vector>
#include <opencv2/core/core.hpp>
#include <opencv2/contrib/contrib.hpp>
#include <opencv2/objdetect/objdetect.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
// #include <opencv2/gpu/gpu.hpp>

// Steps from http://docs.opencv.org/modules/gpu/doc/object_detection.html
 
 int find_face(char* cascade_file, char* face_image)
 {

   cv::CascadeClassifier cascade;
   if(cascade.load(std::string(cascade_file)))
   {
      cv::Mat frame = cv::imread(face_image);
      cv::Mat frame_gray;
      std::vector<cv::Rect> faces;
      cv::cvtColor(frame, frame_gray, CV_BGR2GRAY);
      cv::equalizeHist(frame_gray,frame_gray);
      cascade.detectMultiScale( frame_gray, faces, 1.1, 2, 0 |CV_HAAR_SCALE_IMAGE, cv::Size(30, 30) );
      for(int i = 0; i < (int)faces.size(); ++i)
      {
         cv::Point pt1 = faces[i].tl();
         cv::Size sz = faces[i].size();
         cv::Point pt2(pt1.x+sz.width, pt1.y+sz.height);
         cv::rectangle(frame, pt1, pt2, cv::Scalar(255));
      }
      cv::imshow("faces", frame);
      cv::waitKey(0);
   }
   else
   {
      std::cout << "Error: " << cascade_file << " is not a valid haarcascade file" << std::endl;
      return 1;
   }
   return 0;
}

// // GPU version
// int find_face(char* cascade_file, char* face_image)
// {
//   cv::gpu::CascadeClassifier_GPU cascade_gpu;
//   int gpu_count = cv::gpu::getCudaEnabledDeviceCount();   // gpu_count >0 if CUDA device detected
//   if(gpu_count == 0)
//   {
//     std::cout << "Error: No GPU" << std::endl;
//     return 1;
//   }
//   if(cascade_gpu.load(std::string(cascade_file)))
//   {
//     cv::Mat frame = cv::imread(face_image);
//     cv::gpu::GpuMat faces;
//     cv::Mat frame_gray;
//     cv::cvtColor(frame, frame_gray, CV_BGR2GRAY);
//     cv::gpu::GpuMat gray_gpu(frame_gray);  // copy the gray image to GPU memory
//     cv::equalizeHist(frame_gray,frame_gray);
//     int detect_num = cascade_gpu.detectMultiScale(gray_gpu, faces,1.2, 4, cv::Size(20, 20) );
//     cv::Mat obj_host;
//     faces.colRange(0, detect_num).download(obj_host);  // retrieve results from GPU
//     cv::Rect* cfaces = obj_host.ptr<cv::Rect>();  // results are now in "obj_host"
//     for(int i = 0; i < detect_num; ++i)
//     {
//       // Draw faces
//       cv::Point pt1 = cfaces[i].tl();
//       cv::Size sz = cfaces[i].size();
//       cv::Point pt2(pt1.x+sz.width, pt1.y+sz.height);
//       cv::rectangle(frame, pt1, pt2, cv::Scalar(255));
//       }
//       cv::imshow("faces", frame);
//       cv::waitKey(0);
//     }
//   }
//   else
//   {
//     std::cout << "Error: " << cascade_file << " is not a valid haarcascade file" << std::endl;
//     return 1;
//   }
//   return 0;
// }

opencv_facedetect.i

%module opencv_facedetect
%{
extern int find_face(char* cascade_file, char* face_image);
%}

extern int find_face(char* cascade_file, char* face_image);

Hello I have followed all of your step. However in command g++ -Wall -fPIC -c opencv_facedetect_wrap.cxx pkg-config --cflags python ,I got an error which declared that 'cv' has not been declared. How can I fixed this?