Opencv – the cascadeclassifier in Java cannot find a face with a webcam

I tried to translate opencv cascade classifier tutorial from C to Java Works well in C This Java Tutorial works normally

But the translator didn't detect the face at all I have no definite mistake I can see video input processed from webcam (grayscale / histogram...) and video display Cascading loads does not produce errors But the cascadeclassifier call just doesn't return any faces... So you may be able to skip all the code and just go to my cascadeclassifier call until the public mat detection (mat input frame) Since I'm new to Java and opencv, I paste the rest (I delete anything I think may not be important) just in case, but it doesn't mean you have to debug

I've tried this phone (and other parts) in many different ways, and there's nothing... Lack of ideas

thank you!!

import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;

import org.opencv.core.Mat;
import org.opencv.core.MatOfRect;
import org.opencv.highgui.VideoCapture;
import org.opencv.imgproc.Imgproc;
import org.opencv.objdetect.CascadeClassifier;

class My_Panel extends JPanel{

    private static final long serialVersionUID = 1L;
    private BufferedImage image;
    private CascadeClassifier face_cascade;

    // Create a constructor method
    public My_Panel(){
        super(); 
        String face_cascade_name = "/haarcascade_frontalface_alt.xml";
        //String face_cascade_name = "/lbpcascade_frontalface.xml";
        //-- 1. Load the cascades

        String str;
        str = getClass().getResource(face_cascade_name).getPath();
        str = str.replace("/C:","C:");
        face_cascade_name=str;

        face_cascade=new CascadeClassifier(face_cascade_name);
        if( !face_cascade.empty())
        {
            System.out.println("--(!)Error loading A\n");
            return;
        }
        else
        {
                System.out.println("Face classifier loooaaaaaded up");
        }
    }

    private BufferedImage getimage(){
        return image;
    }

    public void setimage(BufferedImage newimage){
        image=newimage;
        return;
    }

    /**
     * Converts/writes a Mat into a BufferedImage.
     * 
     * @param matrix Mat of type CV_8UC3 or CV_8UC1
     * @return BufferedImage of type TYPE_3BYTE_BGR or TYPE_BYTE_GRAY
     */
    public BufferedImage matToBufferedImage(Mat matrix) {
        int cols = matrix.cols();
        int rows = matrix.rows();
        int elemSize = (int)matrix.elemSize();
        byte[] data = new byte[cols * rows * elemSize];
        int type;

        matrix.get(0,data);

        switch (matrix.channels()) {
            case 1:
                type = BufferedImage.TYPE_BYTE_GRAY;
                break;

            case 3: 
                type = BufferedImage.TYPE_3BYTE_BGR;

                // bgr to rgb
                byte b;
                for(int i=0; i<data.length; i=i+3) {
                    b = data[i];
                    data[i] = data[i+2];
                    data[i+2] = b;
                }
                break;

            default:
                return null;
        }

        BufferedImage image2 = new BufferedImage(cols,rows,type);
        image2.getRaster().setDataElements(0,cols,data);

        return image2;
    }

    public void paintComponent(Graphics g){
         BufferedImage temp=getimage();
         g.drawImage(temp,10,temp.getWidth(),temp.getHeight(),this); 
    }

    public Mat detect(Mat inputframe){
        Mat mRgba=new Mat();
        Mat mGrey=new Mat();
        MatOfRect faces = new MatOfRect();
        //MatOfRect eyes = new MatOfRect();

        inputframe.copyTo(mRgba);
        inputframe.copyTo(mGrey);
        Imgproc.cvtColor( mRgba,mGrey,Imgproc.COLOR_BGR2GRAY);
        Imgproc.equalizeHist( mGrey,mGrey );

        face_cascade.detectMultiScale(mGrey,faces);
        //face_cascade.detectMultiScale(mGrey,faces,1.1,2,0|Objdetect.CASCADE_SCALE_IMAGE,new Size(30,30),new Size(200,200) );
        //face_cascade.detectMultiScale(mGrey,2//CV_HAAR_SCALE_IMAGE,//,200) );

        System.out.println(String.format("Detected %s faces",faces.toArray().length));

        return mGrey;
        }
}

public class window {
    public static void main(String arg[]){
     // Load the native library.
     System.loadLibrary("opencv_java245");  

     String window_name = "Capture - Face detection";

     JFrame frame = new JFrame(window_name);
     frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
     frame.setSize(400,400);

     My_Panel my_panel = new My_Panel();
     frame.setContentPane(my_panel);          
     frame.setVisible(true);           

     //-- 2. Read the video stream
     BufferedImage temp;
     Mat webcam_image=new Mat();

     VideoCapture capture =new VideoCapture(0); 
     if( capture.isOpened())
        {
          while( true )
          {
              capture.read(webcam_image);
              if( !webcam_image.empty() )
               { 
                   frame.setSize(webcam_image.width()+40,webcam_image.height()+60);

                   //-- 3. Apply the classifier to the captured image
                   // At this point I was wondering where this should be done.
                   // I put it within the panel class,but maybe one Could actually
                   // create a processor object...
                   webcam_image=my_panel.detect(webcam_image);

                 //-- 4. Display the image
                   temp=my_panel.matToBufferedImage(webcam_image);
                   my_panel.setimage(temp);
                   my_panel.repaint(); 
               }
               else
               { 
                   System.out.println(" --(!) No captured frame -- Break!"); 
                   break; 
               }
              }
           }
           return;
    }
}

PS.: other information, just in case:

>Mgrey is: mat [480 * 640 * cv_8uc1, iscont = true, issubmat = false, nativeobj = 0x19d9af48, dataaddr = 0x19dc3430] > face is: mat [0 * 0 * cv_8uc1, iscont = false, nativeobj = 0x194bb048, dataaddr = 0x0]

Solution

I've tried your code and it works! haarcascade_ frontalface_ There is only one problem with the location of the alt.xml file Try using the full path of the file: face_ cascade = new CascadeClassifier(“D：/HelloCV/src/haarcascade_frontalface_alt.xml”);