Example usage for org.opencv.objdetect HOGDescriptor detectMultiScale

Introduction

In this page you can find the example usage for org.opencv.objdetect HOGDescriptor detectMultiScale.

Prototype

public void detectMultiScale(Mat img, MatOfRect foundLocations, MatOfDouble foundWeights, double hitThreshold,
            Size winStride, Size padding, double scale, double finalThreshold, boolean useMeanshiftGrouping) 

Source Link

Usage

From source file:usefull.hogPeopleDetection.java

License:LGPL

public static void main(String[] args) throws InterruptedException {

    // load the Core OpenCV library by name

    System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

    // create video capture device object

    VideoCapture cap = new VideoCapture();

    // try to use the hardware device if present

    int CAM_TO_USE = 0;

    // create a new image object

    Mat matFrame = new Mat();

    // try to open first capture device (0)

    try {//from w  w  w  . j av  a2s.c o  m
        cap.open(CAM_TO_USE);
    } catch (Exception e1) {
        System.out.println("No webcam attached");

        // otherwise try opening a video file 

        try {
            cap.open("files/video.mp4");
        } catch (Exception e2) {
            System.out.println("No video file found");
        }
    }

    // if the a video capture source is now open

    if (cap.isOpened()) {

        // create a new window object

        Imshow ims = new Imshow("HOG People Detection");

        boolean keepProcessing = true;

        // create new HoG detection object

        HOGDescriptor HOG = new HOGDescriptor();
        HOG.setSVMDetector(HOGDescriptor.getDefaultPeopleDetector());

        // create 

        MatOfRect foundLocations = new MatOfRect();
        MatOfDouble foundWeights = new MatOfDouble();

        while (keepProcessing) {
            // grab the next frame from video source

            cap.grab();

            // decode and return the grabbed video frame

            cap.retrieve(matFrame);

            // if the frame is valid (not end of video for example)

            if (!(matFrame.empty())) {
                // perform detection

                HOG.detectMultiScale(matFrame, foundLocations, foundWeights, 0, new Size(8, 8),
                        new Size(32, 32), 1.05, 8, false);

                List<Rect> rectangles = foundLocations.toList();

                for (int i = 0; i < rectangles.size(); i++) {

                    Core.rectangle(matFrame, new Point(rectangles.get(i).x, rectangles.get(i).y),
                            new Point(rectangles.get(i).x + rectangles.get(i).width,
                                    rectangles.get(i).y + rectangles.get(i).height),
                            new Scalar(255, 0, 0), 2, 1, 0);
                }

                // display image with a delay of 40ms (i.e. 1000 ms / 25 = 25 fps)

                ims.showImage(matFrame);
                Thread.sleep(40);
            } else {
                keepProcessing = false;
            }
        }

    } else {
        System.out.println("error cannot open any capture source - exiting");
    }

    // close down the camera correctly

    cap.release();

}

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