opencv 3.0 cascade_gpu example source code

opencv 2.49 example is here
http://study.marearts.com/2014/09/opencv-face-detection-using-adaboost.html

#include < iostream>    
#include "opencv2\objdetect\objdetect.hpp"
#include "opencv2\highgui\highgui.hpp"
#include "opencv2\imgproc\imgproc.hpp"
#include "opencv2\cudaobjdetect.hpp"
#include "opencv2\cudaimgproc.hpp"

#ifdef _DEBUG               
#pragma comment(lib, "opencv_core300d.lib")       
#pragma comment(lib, "opencv_highgui300d.lib")    
#pragma comment(lib, "opencv_imgcodecs300d.lib")  
#pragma comment(lib, "opencv_objdetect300d.lib")  
#pragma comment(lib, "opencv_imgproc300d.lib")  
#pragma comment(lib, "opencv_cudaobjdetect300d.lib")  
#else       
#pragma comment(lib, "opencv_core300.lib")       
#pragma comment(lib, "opencv_highgui300.lib")    
#pragma comment(lib, "opencv_imgcodecs300.lib")    
#pragma comment(lib, "opencv_objdetect300.lib")  
#pragma comment(lib, "opencv_imgproc300.lib")  
#pragma comment(lib, "opencv_cudaobjdetect300.lib")  
#endif        

using namespace std;
using namespace cv;


void main()
{
 //for time measure  
 float TakeTime;
 unsigned long Atime, Btime;

 //window  
 namedWindow("origin");

 //load image  
 Mat img = imread("sh.jpg");
 Mat grayImg; //adaboost detection is gray input only.  
 cvtColor(img, grayImg, CV_BGR2GRAY);

 //load xml file  
 string trainface = ".\\haarcascade_frontalface_alt.xml";

 //declaration  
 Ptr< cuda::CascadeClassifier> cascade_gpu = cuda::CascadeClassifier::create(trainface);

 
 /////////////////////////////////////////////  
 
 //gpu case face detection code  
 cuda::GpuMat faceBuf_gpu;
 cuda::GpuMat GpuImg;
 vector< Rect> faces;

 GpuImg.upload(grayImg);
 Atime = getTickCount();

 cascade_gpu->detectMultiScale(GpuImg, faceBuf_gpu);
 cascade_gpu->convert(faceBuf_gpu, faces);
 Btime = getTickCount();
 TakeTime = (Btime - Atime) / getTickFrequency();
 printf("detected face(gpu version) =%d / %lf sec take.\n", faces.size(), TakeTime);
 Mat faces_downloaded;
 if (faces.size() >= 1)
 {
  for (size_t i = 0; i < faces.size(); ++i)
   rectangle(img, faces[i], Scalar(255));
 } 

 /////////////////////////////////////////////////  
 //result display  
 imshow("origin", img);
 waitKey(0);
}