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example_15-BackgroundSubtractor.cpp
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example_15-BackgroundSubtractor.cpp
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// EXTRA Example 15-6, using OpenCV's background subtractor class. Modified by Gary Bradski, 6/4/2017
#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>
using namespace cv;
using namespace std;
// Global variables
Mat frame; //current frame
Mat fgMaskMOG2; //fg mask fg mask generated by MOG2 method
Mat theBackground; //Will hold the current background image as seen from the model
Ptr<BackgroundSubtractor> pMOG2; //MOG2 Background subtractor
int keyboard; //input from keyboard
void help();
void processVideo(char* videoFilename, int train);
void processImages(char* firstFrameFilename, int train);
void help()
{
cout
<< "\n-----------Taken from tutorial_background_subtraction.html---------------\n" << endl
<< "This program shows how to use background subtraction methods provided by " << endl
<< " OpenCV (BackgroundSubtractor class). " << endl
<< "You can process both videos (-vid) and images (-img)." << endl
<< " We pass it #framesTraining which is the number of frames or images to train on before starting background subtraction\n"
<< endl
<< "Usage:" << endl
<< "./example_15-BackgroundSubtractor {<#framesTraining> -vid <video filename>|-img <image filename>}\n" << endl
<< "for example: ./example_15-BackgroundSubtractor 50 -vid ../tree.avi" << endl
<< "or: ./example_15-BackgroundSubtractor 20 -img /data/images/1.png" << endl
<< "\n" << endl
<< "This file demonstrates the MOG2 class, you can go to opencv docs to see" << endl
<< "other techniques. Each technique has it's own way of setting thresholds etc."<< endl
<< "We keep it generic here, so the results are mediocre. You must go in and" << endl
<< "look up how to set the particular thresholds etc to get good results!" << endl
<< "--------------------------------------------------------------------------" << endl
<< endl;
}
int main(int argc, char* argv[])
{
//print help information
help();
//check for the input parameter correctness
if(argc != 4) {
cerr <<"Incorret input list" << endl;
cerr <<"exiting..." << endl;
return EXIT_FAILURE;
}
//create GUI windows
namedWindow("Frame");
namedWindow("theBackground");
namedWindow("FG Mask MOG 2");
int number_to_train_on = atoi( argv[1] ); //Read the number of frames to train on
//create Background Subtractor objects
pMOG2 = createBackgroundSubtractorMOG2(); //MOG2 approach
if(strcmp(argv[2], "-vid") == 0) {
//input data coming from a video
processVideo(argv[3], number_to_train_on);
}
else if(strcmp(argv[2], "-img") == 0) {
//input data coming from a sequence of images
processImages(argv[3], number_to_train_on);
}
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;
}
void processVideo(char* videoFilename, int train) {
//create the capture object
VideoCapture capture(videoFilename);
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
double learning_rate = 0.1;
int frame_count = 0;
while( (char)keyboard != 'q' && (char)keyboard != 27 ){
//read the current frame
if(!capture.read(frame)) {
cerr << "Unable to read next frame." << endl;
cerr << "Exiting..." << endl;
exit(EXIT_FAILURE);
}
frame_count = int(capture.get(CAP_PROP_POS_FRAMES)); //get frame#
//update the background model
//
//NOTE: This file just demonstrates the generic methods, each class
// Has specific ways of setting thresholds etc to make it work well.
// You must go into the documentation (for MOG2, see classcv_1_1BackgroundSubtractorMOG2
// if you want to get good results!
//
if(frame_count == train) { learning_rate = 0;} //stop learning after training
pMOG2->apply(frame, fgMaskMOG2, learning_rate);
//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);
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);
pMOG2->getBackgroundImage(theBackground); //Get an image of the model's background
imshow("theBackground",theBackground);
/* By uncommenting this, you can write out the mask images
string imageToSave = "output_MOG_" + frameNumberString + ".png";
bool saved = imwrite(imageToSave, fgMaskMOG);
if(!saved) {
cerr << "Unable to save " << imageToSave << endl;
}
*/
//get the input from the keyboard
if(frame_count >= train) {
cout << "\nHit any key to continue\n" << endl;
keyboard = waitKey(); //single step with keyboard press in run mode
} else {
keyboard = waitKey( 10 ); //run automatically in train mode
}
}
//delete capture object
capture.release();
}
void processImages(char* fistFrameFilename, int train) {
//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
double learning_rate = 0.1;
int frame_count = 0;
while( (char)keyboard != 'q' && (char)keyboard != 27 ){
//update the background model
//
//NOTE: This file just demonstrates the generic methods, each class
// Has specific ways of setting thresholds etc to make it work well.
// You must go into the documentation (for MOG2, see classcv_1_1BackgroundSubtractorMOG2
// if you want to get good results!
//
if(frame_count == train) { learning_rate = 0;} //stop learning after training
pMOG2->apply(frame, fgMaskMOG2, learning_rate);
//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 the current frame and the fg masks
imshow("Frame", frame);
imshow("FG Mask MOG 2", fgMaskMOG2);
pMOG2->getBackgroundImage(theBackground); //Get an image of the model's background
imshow("theBackground",theBackground);
/* By uncommenting this, you can write out the mask images
string imageToSave = "output_MOG_" + frameNumberString + ".png";
bool saved = imwrite(imageToSave, fgMaskMOG);
if(!saved) {
cerr << "Unable to save " << imageToSave << endl;
}
*/
//get the input from the keyboard
if(frame_count >= train) {
cout << "\nHit any key to continue\n" << endl;
keyboard = waitKey(); //Single step with keyboard press in test mode
} else {
keyboard = waitKey( 10 ); //Run automatically in train mode
}
frame_count += 1;
//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);
}
}