Re-add peopledetect.cpp sample.

samples/cpp/peopledetect.cpp

+#include <opencv2/objdetect.hpp>
+#include <opencv2/highgui.hpp>
+#include <opencv2/imgproc.hpp>
+#include <iostream>
+
+using namespace cv;
+using namespace std;
+
+
+static void help()
+{
+    cout << "\nThis program demonstrates the use of the HoG descriptor using\n"
+            "  HOGDescriptor::hog.setSVMDetector(HOGDescriptor::getDefaultPeopleDetector());\n"
+            "Usage:\n"
+            "./peopledetect --i=<image_filename> | --d=<image_directory>\n\n"
+            "During execution:\n\tHit q or ESC key to quit.\n"
+            "\tUsing OpenCV version " << CV_VERSION << "\n" << endl;
+}
+
+const char* keys =
+{
+    "{help h||}"
+    "{image i| ../data/basketball2.png|input image name}"
+    "{directory d||images directory}"
+};
+
+static void detectAndDraw(const HOGDescriptor &hog, Mat &img)
+{
+    vector<Rect> found, found_filtered;
+    double t = (double) getTickCount();
+    // 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).
+    hog.detectMultiScale(img, found, 0, Size(8,8), Size(32,32), 1.05, 2);
+    t = (double) getTickCount() - t;
+    cout << "detection time = " << (t*1000./cv::getTickFrequency()) << " ms" << endl;
+
+    for(size_t i = 0; i < found.size(); i++ )
+    {
+        Rect r = found[i];
+
+        size_t j;
+        // Do not add small detections inside a bigger detection.
+        for ( j = 0; j < found.size(); j++ )
+            if ( j != i && (r & found[j]) == r )
+                break;
+
+        if ( j == found.size() )
+            found_filtered.push_back(r);
+    }
+
+    for (size_t i = 0; i < found_filtered.size(); i++)
+    {
+        Rect r = found_filtered[i];
+
+        // 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);
+        rectangle(img, r.tl(), r.br(), cv::Scalar(0,255,0), 3);
+    }
+}
+
+int main(int argc, char** argv)
+{
+    CommandLineParser parser(argc, argv, keys);
+
+    if (parser.has("help"))
+    {
+        help();
+        return 0;
+    }
+
+    HOGDescriptor hog;
+    hog.setSVMDetector(HOGDescriptor::getDefaultPeopleDetector());
+    namedWindow("people detector", 1);
+
+    string pattern_glob = "";
+    if (parser.has("directory"))
+    {
+        pattern_glob = parser.get<string>("directory");
+    }
+    else if (parser.has("image"))
+    {
+        pattern_glob = parser.get<string>("image");
+    }
+
+    if (!pattern_glob.empty())
+    {
+        vector<String> filenames;
+        String folder(pattern_glob);
+        glob(folder, filenames);
+
+        for (vector<String>::const_iterator it = filenames.begin(); it != filenames.end(); ++it)
+        {
+            cout << "\nRead: " << *it << endl;
+            // Read current image
+            Mat current_image = imread(*it);
+
+            if (current_image.empty())
+                continue;
+
+            detectAndDraw(hog, current_image);
+
+            imshow("people detector", current_image);
+            int c = waitKey(0) & 255;
+            if ( c == 'q' || c == 'Q' || c == 27)
+                break;
+        }
+    }
+
+    return 0;
+}