face detection in Qt and opencv

Question

I wrote some code for face detection in c++ using the opencv library. Here I am controlling the mouse pointer using face. When I write the same code in Qt, it does not load the haarcascade xml files

Here is my c++ code:

#include<opencv2/opencv.hpp> 
#include<opencv2/highgui/highgui.hpp>
#include<time.h>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
using namespace cv;

CascadeClassifier faceCade;

String faceCascadeName = "lbpcascade_frontalface.xml";
String FaceDetectWindow = "Face Detector Window";
String FaceDetectGrayWindow = "Face Detector Gray Window";


int main() {

    VideoCapture cap(0);
    Mat camFrames, grayFrames;
    vector<Rect> faces;
    long imageIndex = 0;

    int preX=0,preY=0;
    int j=0;

     if( !faceCade.load( faceCascadeName ) ){ cout<<"--(!)Error loading\n"; return -1; };

    while (1) {
        cap >> camFrames;

        cvtColor(camFrames, grayFrames, CV_BGR2GRAY);
        equalizeHist(grayFrames, grayFrames);

        faceCade.detectMultiScale(grayFrames, faces, 1.1, 2, 0, Size(160, 160));

        for (int i = 0; i < faces.size(); i++)
      {
            Mat faceROI = grayFrames(faces[i]);

            rectangle(camFrames, Rect(faces[i].x - 25,faces[i].y - 25,faces[i].width + 35 ,faces[i].height + 35),  Scalar(0, 0, 255), 1, 1, 0);

            Point center(faces[i].x + faces[i].width * 0.5,faces[i].y + faces[i].height * 0.5);


            cout<<"\nx = "<<faces[i].x<<"\ty = "<<faces[i].y;

            //while(j==10)
            //{
             if((faces[i].y<125)&&(faces[i].x<255))
             {
                printf("  RU");
                system("xte 'mousermove 10 -10'");
                }
             else if((faces[i].y>185)&&(faces[i].x<255)){
                  printf("  RD");
                  system("xte 'mousermove 10 10'");
                  }
             else if((faces[i].y>185)&&(faces[i].x>305)){
                  printf("  LD");
                  system("xte 'mousermove -10 10'");
                  }
             else if((faces[i].y<125)&&(faces[i].x<255)){
                  printf("  LU");
                  system("xte 'mousermove -10 -10'");
                  }
              else if((faces[i].y>185)&&(faces[i].x>255)&&(faces[i].x<305)){
                  printf("  Down");
                  system("xte 'mousermove 0 10'");
                  }
               else if((faces[i].y<125)&&(faces[i].x>255)&&(faces[i].x<305)){
                  printf("  up");
                  system("xte 'mousermove 0 -10'");
                  }
              else if((faces[i].y>125)&&(faces[i].y<185)&&(faces[i].x<255)){
                  printf("  L");
                  system("xte 'mousermove -10 0'");
                  }
             else if((faces[i].y>125)&&(faces[i].y<185)&&(faces[i].x>305)){
                  printf("  R");
                  system("xte 'mousermove 10 0'");
                  }
               preX = faces[i].x;
               preY   = faces[i].y;
               j=0;
              }
        //j++;
        //}

        imshow(FaceDetectWindow, camFrames);
        imshow(FaceDetectGrayWindow, grayFrames);
        if(waitKey(30) >= 0) break;

    }

}

here the face is detected but in the qt code below it is not working

#include<opencv2/opencv.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<time.h>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
using namespace cv;

CascadeClassifier faceCade;

String faceCascadeName = ":/new/prefix1/lbpcascade_frontalface.xml";
String FaceDetectWindow = "Face Detector Window";
String FaceDetectGrayWindow = "Face Detector Gray Window";


int main() {

    VideoCapture cap(0);
    Mat camFrames, grayFrames;
    vector<Rect> faces;
    long imageIndex = 0;

    int preX=0,preY=0;
    int j=0;

    if( !faceCade.load( "lbpcascade_frontalface.xml" ) ){ cout<<"--(!)Error loading\n"; return -1; };

    while (1) {
        cap >> camFrames;

        cvtColor(camFrames, grayFrames, CV_BGR2GRAY);
        equalizeHist(grayFrames, grayFrames);

        faceCade.detectMultiScale(grayFrames, faces, 1.1, 2, 0, Size(80, 80));

    /*    for (int i = 0; i < faces.size(); i++)
      {
            Mat faceROI = grayFrames(faces[i]);

            rectangle(camFrames, Rect(faces[i].x - 25,faces[i].y - 25,faces[i].width + 35 ,faces[i].height + 35),  Scalar(0, 0, 255), 1, 1, 0);

            Point center(faces[i].x + faces[i].width * 0.5,faces[i].y + faces[i].height * 0.5);


            cout<<"\nx = "<<faces[i].x<<"\ty = "<<faces[i].y;

            //while(j==10)
            //{
             if((faces[i].y<125)&&(faces[i].x<255))
             {
                printf("  RU");
                system("xte 'mousermove 10 -10'");
                }
             else if((faces[i].y>185)&&(faces[i].x<255)){
                  printf("  RD");
                  system("xte 'mousermove 10 10'");
                  }
             else if((faces[i].y>185)&&(faces[i].x>305)){
                  printf("  LD");
                  system("xte 'mousermove -10 10'");
                  }
             else if((faces[i].y<125)&&(faces[i].x<255)){
                  printf("  LU");
                  system("xte 'mousermove -10 -10'");
                  }
              else if((faces[i].y>185)&&(faces[i].x>255)&&(faces[i].x<305)){
                  printf("  Down");
                  system("xte 'mousermove 0 10'");
                  }
               else if((faces[i].y<125)&&(faces[i].x>255)&&(faces[i].x<305)){
                  printf("  up");
                  system("xte 'mousermove 0 -10'");
                  }
              else if((faces[i].y>125)&&(faces[i].y<185)&&(faces[i].x<255)){
                  printf("  L");
                  system("xte 'mousermove -10 0'");
                  }
             else if((faces[i].y>125)&&(faces[i].y<185)&&(faces[i].x>305)){
                  printf("  R");
                  system("xte 'mousermove 10 0'");
                  }
               preX = faces[i].x;
               preY   = faces[i].y;
               j=0;
              }
            //j++;
        //}*/

        imshow(FaceDetectWindow, camFrames);
        imshow(FaceDetectGrayWindow, grayFrames);
        if(waitKey(30) >= 0) break;

    }

}

please help me to do that in qt platform here the output shown in qt code is --(!)Error loading which means the cascade file is not loaded

Answer 1

String faceCascadeName = ":/new/prefix1/lbpcascade_frontalface.xml";

It is a valid path, but you need to create it in the Qt resource file.

http://qt-project.org/doc/qt-5.0/qtcore/resources.html

Otherwise, if you don't want to deal with resources, go and make it a relative path.

For example:

"./file.xml" will look for the xml file from the working directory.

"../file.xml" will look for the xml file one level above the working directory.

Hope that helps.

Answer 2

The following path does not seem to be correct:

String faceCascadeName = ":/new/prefix1/lbpcascade_frontalface.xml";