| OpenCV 4.3.0 Open Source Computer Vision

samples/cpp/peopledetect.cpp
// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html
#include <opencv2/objdetect.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/videoio.hpp>
#include <iostream>
#include <iomanip>
using namespace cv;
using namespace std;
class Detector
{
enum Mode { Default, Daimler } m;
HOGDescriptor hog, hog_d;
public:
Detector() : m(Default), hog(), hog_d(Size(48, 96), Size(16, 16), Size(8, 8), Size(8, 8), 9)
{
hog.setSVMDetector(HOGDescriptor::getDefaultPeopleDetector());
hog_d.setSVMDetector(HOGDescriptor::getDaimlerPeopleDetector());
}
void toggleMode() { m = (m == Default ? Daimler : Default); }
string modeName() const { return (m == Default ? "Default" : "Daimler"); }
vector<Rect> detect(InputArray img)
{
// Run the detector with default parameters. to get a higher hit-rate
// (and more false alarms, respectively), decrease the hitThreshold and
// groupThreshold (set groupThreshold to 0 to turn off the grouping completely).
vector<Rect> found;
if (m == Default)
hog.detectMultiScale(img, found, 0, Size(8,8), Size(), 1.05, 2, false);
else if (m == Daimler)
hog_d.detectMultiScale(img, found, 0, Size(8,8), Size(), 1.05, 2, true);
return found;
}
void adjustRect(Rect & r) const
{
// The HOG detector returns slightly larger rectangles than the real objects,
// so we slightly shrink the rectangles to get a nicer output.
r.x += cvRound(r.width*0.1);
r.width = cvRound(r.width*0.8);
r.y += cvRound(r.height*0.07);
r.height = cvRound(r.height*0.8);
}
};
static const string keys = "{ help h | | print help message }"
"{ camera c | 0 | capture video from camera (device index starting from 0) }"
"{ video v | | use video as input }";
int main(int argc, char** argv)
{
CommandLineParser parser(argc, argv, keys);
parser.about("This sample demonstrates the use of the HoG descriptor.");
if (parser.has("help"))
{
parser.printMessage();
return 0;
}
int camera = parser.get<int>("camera");
string file = parser.get<string>("video");
if (!parser.check())
{
parser.printErrors();
return 1;
}
VideoCapture cap;
if (file.empty())
cap.open(camera);
else
{
file = samples::findFileOrKeep(file);
cap.open(file);
}
if (!cap.isOpened())
{
cout << "Can not open video stream: '" << (file.empty() ? "<camera>" : file) << "'" << endl;
return 2;
}
cout << "Press 'q' or <ESC> to quit." << endl;
cout << "Press <space> to toggle between Default and Daimler detector" << endl;
Detector detector;
Mat frame;
for (;;)
{
cap >> frame;
if (frame.empty())
{
cout << "Finished reading: empty frame" << endl;
break;
}
int64 t = getTickCount();
vector<Rect> found = detector.detect(frame);
t = getTickCount() - t;
// show the window
{
ostringstream buf;
buf << "Mode: " << detector.modeName() << " ||| "
<< "FPS: " << fixed << setprecision(1) << (getTickFrequency() / (double)t);
putText(frame, buf.str(), Point(10, 30), FONT_HERSHEY_PLAIN, 2.0, Scalar(0, 0, 255), 2, LINE_AA);
}
for (vector<Rect>::iterator i = found.begin(); i != found.end(); ++i)
{
Rect &r = *i;
detector.adjustRect(r);
rectangle(frame, r.tl(), r.br(), cv::Scalar(0, 255, 0), 2);
}
imshow("People detector", frame);
// interact with user
const char key = (char)waitKey(1);
if (key == 27 || key == 'q') // ESC
{
cout << "Exit requested" << endl;
break;
}
else if (key == ' ')
{
detector.toggleMode();
}
}
return 0;
}