Update background subtraction tutorial with Java and Python codes.

doc/tutorials/video/table_of_content_video.markdown

@@ -6,6 +6,8 @@ tracking and foreground extractions.
 
 -   @subpage tutorial_background_subtraction
 
+    *Languages:* C++, Java, Python
+
     *Compatibility:* \> OpenCV 2.4.6
 
     *Author:* Domenico Daniele Bloisi

samples/cpp/tutorial_code/video/bg_sub.cpp

@@ -4,180 +4,84 @@
  * @author Domenico D. Bloisi
  */
 
-//opencv
-#include "opencv2/imgcodecs.hpp"
-#include "opencv2/imgproc.hpp"
-#include "opencv2/videoio.hpp"
-#include <opencv2/highgui.hpp>
-#include <opencv2/video.hpp>
-//C
-#include <stdio.h>
-//C++
 #include <iostream>
 #include <sstream>
+#include <opencv2/imgcodecs.hpp>
+#include <opencv2/imgproc.hpp>
+#include <opencv2/videoio.hpp>
+#include <opencv2/highgui.hpp>
+#include <opencv2/video.hpp>
 
 using namespace cv;
 using namespace std;
 
-// Global variables
-Mat frame; //current frame
-Mat fgMaskMOG2; //fg mask fg mask generated by MOG2 method
-Ptr<BackgroundSubtractor> pMOG2; //MOG2 Background subtractor
-char keyboard; //input from keyboard
-
-/** Function Headers */
-void help();
-void processVideo(char* videoFilename);
-void processImages(char* firstFrameFilename);
+const char* params
+    = "{ help h         |                   | Print usage }"
+      "{ input          | ../data/vtest.avi | Path to a video or a sequence of image }"
+      "{ algo           | MOG2              | Background subtraction method (KNN, MOG2) }";
 
-void help()
-{
-    cout
-    << "--------------------------------------------------------------------------" << endl
-    << "This program shows how to use background subtraction methods provided by "  << endl
-    << " OpenCV. You can process both videos (-vid) and images (-img)."             << endl
-                                                                                    << endl
-    << "Usage:"                                                                     << endl
-    << "./bg_sub {-vid <video filename>|-img <image filename>}"                     << endl
-    << "for example: ./bg_sub -vid video.avi"                                       << endl
-    << "or: ./bg_sub -img /data/images/1.png"                                       << endl
-    << "--------------------------------------------------------------------------" << endl
-    << endl;
-}
-
-/**
- * @function main
- */
 int main(int argc, char* argv[])
 {
+    CommandLineParser parser(argc, argv, params);
+    parser.about( "This program shows how to use background subtraction methods provided by "
+                  " OpenCV. You can process both videos and images.\n" );
+    if (parser.has("help"))
+    {
         //print help information
-    help();
-
-    //check for the input parameter correctness
-    if(argc != 3) {
-        cerr <<"Incorret input list" << endl;
-        cerr <<"exiting..." << endl;
-        return EXIT_FAILURE;
+        parser.printMessage();
     }
 
-    //create GUI windows
-    namedWindow("Frame");
-    namedWindow("FG Mask MOG 2");
-
+    //! [create]
     //create Background Subtractor objects
-    pMOG2 = createBackgroundSubtractorMOG2(); //MOG2 approach
-
-    if(strcmp(argv[1], "-vid") == 0) {
-        //input data coming from a video
-        processVideo(argv[2]);
-    }
-    else if(strcmp(argv[1], "-img") == 0) {
-        //input data coming from a sequence of images
-        processImages(argv[2]);
-    }
-    else {
-        //error in reading input parameters
-        cerr <<"Please, check the input parameters." << endl;
-        cerr <<"Exiting..." << endl;
-        return EXIT_FAILURE;
-    }
-    //destroy GUI windows
-    destroyAllWindows();
-    return EXIT_SUCCESS;
-}
+    Ptr<BackgroundSubtractor> pBackSub;
+    if (parser.get<String>("algo") == "MOG2")
+        pBackSub = createBackgroundSubtractorMOG2();
+    else
+        pBackSub = createBackgroundSubtractorKNN();
+    //! [create]
 
-/**
- * @function processVideo
- */
-void processVideo(char* videoFilename) {
-    //create the capture object
-    VideoCapture capture(videoFilename);
-    if(!capture.isOpened()){
+    //! [capture]
+    VideoCapture capture(parser.get<String>("input"));
+    if (!capture.isOpened()){
         //error in opening the video input
-        cerr << "Unable to open video file: " << videoFilename << endl;
-        exit(EXIT_FAILURE);
-    }
-    //read input data. ESC or 'q' for quitting
-    keyboard = 0;
-    while( keyboard != 'q' && keyboard != 27 ){
-        //read the current frame
-        if(!capture.read(frame)) {
-            cerr << "Unable to read next frame." << endl;
-            cerr << "Exiting..." << endl;
-            exit(EXIT_FAILURE);
+        cerr << "Unable to open: " << parser.get<String>("input") << endl;
+        return 0;
     }
+    //! [capture]
+
+    Mat frame, fgMask;
+    while (true) {
+        capture >> frame;
+        if (frame.empty())
+            break;
+
+        //! [apply]
         //update the background model
-        pMOG2->apply(frame, fgMaskMOG2);
+        pBackSub->apply(frame, fgMask);
+        //! [apply]
+
+        //! [display_frame_number]
         //get the frame number and write it on the current frame
-        stringstream ss;
         rectangle(frame, cv::Point(10, 2), cv::Point(100,20),
                   cv::Scalar(255,255,255), -1);
+        stringstream ss;
         ss << capture.get(CAP_PROP_POS_FRAMES);
         string frameNumberString = ss.str();
         putText(frame, frameNumberString.c_str(), cv::Point(15, 15),
                 FONT_HERSHEY_SIMPLEX, 0.5 , cv::Scalar(0,0,0));
-        //show the current frame and the fg masks
-        imshow("Frame", frame);
-        imshow("FG Mask MOG 2", fgMaskMOG2);
-        //get the input from the keyboard
-        keyboard = (char)waitKey( 30 );
-    }
-    //delete capture object
-    capture.release();
-}
+        //! [display_frame_number]
 
-/**
- * @function processImages
- */
-void processImages(char* fistFrameFilename) {
-    //read the first file of the sequence
-    frame = imread(fistFrameFilename);
-    if(frame.empty()){
-        //error in opening the first image
-        cerr << "Unable to open first image frame: " << fistFrameFilename << endl;
-        exit(EXIT_FAILURE);
-    }
-    //current image filename
-    string fn(fistFrameFilename);
-    //read input data. ESC or 'q' for quitting
-    keyboard = 0;
-    while( keyboard != 'q' && keyboard != 27 ){
-        //update the background model
-        pMOG2->apply(frame, fgMaskMOG2);
-        //get the frame number and write it on the current frame
-        size_t index = fn.find_last_of("/");
-        if(index == string::npos) {
-            index = fn.find_last_of("\\");
-        }
-        size_t index2 = fn.find_last_of(".");
-        string prefix = fn.substr(0,index+1);
-        string suffix = fn.substr(index2);
-        string frameNumberString = fn.substr(index+1, index2-index-1);
-        istringstream iss(frameNumberString);
-        int frameNumber = 0;
-        iss >> frameNumber;
-        rectangle(frame, cv::Point(10, 2), cv::Point(100,20),
-                  cv::Scalar(255,255,255), -1);
-        putText(frame, frameNumberString.c_str(), cv::Point(15, 15),
-                FONT_HERSHEY_SIMPLEX, 0.5 , cv::Scalar(0,0,0));
+        //! [show]
         //show the current frame and the fg masks
         imshow("Frame", frame);
-        imshow("FG Mask MOG 2", fgMaskMOG2);
+        imshow("FG Mask", fgMask);
+        //! [show]
+
         //get the input from the keyboard
-        keyboard = (char)waitKey( 30 );
-        //search for the next image in the sequence
-        ostringstream oss;
-        oss << (frameNumber + 1);
-        string nextFrameNumberString = oss.str();
-        string nextFrameFilename = prefix + nextFrameNumberString + suffix;
-        //read the next frame
-        frame = imread(nextFrameFilename);
-        if(frame.empty()){
-            //error in opening the next image in the sequence
-            cerr << "Unable to open image frame: " << nextFrameFilename << endl;
-            exit(EXIT_FAILURE);
-        }
-        //update the path of the current frame
-        fn.assign(nextFrameFilename);
+        int keyboard = waitKey(30);
+        if (keyboard == 'q' || keyboard == 27)
+            break;
     }
+
+    return 0;
 }

samples/java/tutorial_code/video/background_subtraction/BackgroundSubtractionDemo.java

+import org.opencv.core.Core;
+import org.opencv.core.Mat;
+import org.opencv.core.Point;
+import org.opencv.core.Scalar;
+import org.opencv.highgui.HighGui;
+import org.opencv.imgproc.Imgproc;
+import org.opencv.video.BackgroundSubtractor;
+import org.opencv.video.Video;
+import org.opencv.videoio.VideoCapture;
+import org.opencv.videoio.Videoio;
+
+class BackgroundSubtraction {
+    public void run(String[] args) {
+        String input = args.length > 0 ? args[0] : "../data/vtest.avi";
+        boolean useMOG2 = args.length > 1 ? args[1] == "MOG2" : true;
+
+        //! [create]
+        BackgroundSubtractor backSub;
+        if (useMOG2) {
+            backSub = Video.createBackgroundSubtractorMOG2();
+        } else {
+            backSub = Video.createBackgroundSubtractorKNN();
+        }
+        //! [create]
+
+        //! [capture]
+        VideoCapture capture = new VideoCapture(input);
+        if (!capture.isOpened()) {
+            System.err.println("Unable to open: " + input);
+            System.exit(0);
+        }
+        //! [capture]
+
+        Mat frame = new Mat(), fgMask = new Mat();
+        while (true) {
+            capture.read(frame);
+            if (frame.empty()) {
+                break;
+            }
+
+            //! [apply]
+            // update the background model
+            backSub.apply(frame, fgMask);
+            //! [apply]
+
+            //! [display_frame_number]
+            // get the frame number and write it on the current frame
+            Imgproc.rectangle(frame, new Point(10, 2), new Point(100, 20), new Scalar(255, 255, 255), -1);
+            String frameNumberString = String.format("%d", (int)capture.get(Videoio.CAP_PROP_POS_FRAMES));
+            Imgproc.putText(frame, frameNumberString, new Point(15, 15), Core.FONT_HERSHEY_SIMPLEX, 0.5,
+                    new Scalar(0, 0, 0));
+            //! [display_frame_number]
+
+            //! [show]
+            // show the current frame and the fg masks
+            HighGui.imshow("Frame", frame);
+            HighGui.imshow("FG Mask", fgMask);
+            //! [show]
+
+            // get the input from the keyboard
+            int keyboard = HighGui.waitKey(30);
+            if (keyboard == 'q' || keyboard == 27) {
+                break;
+            }
+        }
+
+        HighGui.waitKey();
+        System.exit(0);
+    }
+}
+
+public class BackgroundSubtractionDemo {
+    public static void main(String[] args) {
+        // Load the native OpenCV library
+        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
+
+        new BackgroundSubtraction().run(args);
+    }
+}

samples/python/tutorial_code/video/background_subtraction/bg_sub.py

+from __future__ import print_function
+import cv2 as cv
+import argparse
+
+parser = argparse.ArgumentParser(description='This program shows how to use background subtraction methods provided by \
+                                              OpenCV. You can process both videos and images.')
+parser.add_argument('--input', type=str, help='Path to a video or a sequence of image.', default='../data/vtest.avi')
+parser.add_argument('--algo', type=str, help='Background subtraction method (KNN, MOG2).', default='MOG2')
+args = parser.parse_args()
+
+## [create]
+#create Background Subtractor objects
+if args.algo == 'MOG2':
+    backSub = cv.createBackgroundSubtractorMOG2()
+else:
+    backSub = cv.createBackgroundSubtractorKNN()
+## [create]
+
+## [capture]
+capture = cv.VideoCapture(args.input)
+if not capture.isOpened:
+    print('Unable to open: ' + args.input)
+    exit(0)
+## [capture]
+
+while True:
+    ret, frame = capture.read()
+    if frame is None:
+        break
+
+    ## [apply]
+    #update the background model
+    fgMask = backSub.apply(frame)
+    ## [apply]
+
+    ## [display_frame_number]
+    #get the frame number and write it on the current frame
+    cv.rectangle(frame, (10, 2), (100,20), (255,255,255), -1)
+    cv.putText(frame, str(capture.get(cv.CAP_PROP_POS_FRAMES)), (15, 15),
+               cv.FONT_HERSHEY_SIMPLEX, 0.5 , (0,0,0))
+    ## [display_frame_number]
+
+    ## [show]
+    #show the current frame and the fg masks
+    cv.imshow('Frame', frame)
+    cv.imshow('FG Mask', fgMask)
+    ## [show]
+
+    keyboard = cv.waitKey(30)
+    if keyboard == 'q' or keyboard == 27:
+        break