OpenCV:cvCreateGaussianBGModel

/* Demo of the background/foreground detection algorithme */
/* Author: Francois Cauwe */
#include <ctype.h>
#include <stdio.h>
#include <iostream>
#include <string>
#include <sstream>

#include <opencv/cv.h>
#include <opencv/cvaux.h>
#include <opencv/highgui.h>

#define DEBUG false

using namespace std;

int main(int argc, char ** argv)
{
    /* Start capturing */
    CvCapture* capture = 0;

    if (argc == 1 || (argc == 2 && strlen(argv[1]) == 1 && isdigit(argv[1][0]))) {
        capture = cvCaptureFromCAM(argc == 2 ? argv[1][0] - '0' : 0);
    } else if (argc == 2) {
        capture = cvCaptureFromAVI(argv[1]);
        if (DEBUG) cout << "Now capturing from AVI, capture  = " << capture << endl;
    }

    if (DEBUG) {
        cout << "argc = " << argc << ", argv[1] = " << argv[1] << endl;
    }

    if (!capture) {
        fprintf(stderr, "Could not initialize...\n");
        return -1;
    }

    /* print a welcome message, and the OpenCV version */
    printf("Demo of the background classification using CvGaussBGModel %s (%d.%d.%d)\n", CV_VERSION,
    CV_MAJOR_VERSION, CV_MINOR_VERSION, CV_SUBMINOR_VERSION);

    /* Capture 1 video frame for initialization */
    IplImage* videoFrame = NULL;
    videoFrame = cvQueryFrame(capture);

    if (!videoFrame) {
        printf("Bad frame \n");
        exit(0);
    }

    // Create windows
    cvNamedWindow("BG", 1);
    cvNamedWindow("FG", 1);
    cvNamedWindow("Original", 1);
    cvMoveWindow("BG", 670, 0);
    cvMoveWindow("FG", 335, 0);
    cvMoveWindow("Original", 0, 0);

    // Select parameters for Gaussian model.
    CvGaussBGStatModelParams* params = new CvGaussBGStatModelParams;
    params->win_size = 200;
    params->n_gauss = 5;  // cars:5, trees: 2/10
    params->bg_threshold = 0.6;   // cars: 0.7, trees: 0.9, car thief: 0.6
    params->std_threshold = 3.0;  // cars: 3.5, car thief: 3.0
    params->minArea = 5;  // cars: 25, trees: 1
    params->weight_init = 0.05;
    params->variance_init = 50;

    // Creat CvBGStatModel
    // cvCreateGaussianBGModel( IplImage* first_frame, CvGaussBGStatModelParams* parameters )
    // or
    // cvCreateGaussianBGModel( IplImage* first_frame )
    CvBGStatModel* bgModel = cvCreateGaussianBGModel(videoFrame, params);

    int key = -1;
    int frameNr = 0;
    while (key != 'q') {
        // Grab a frame
        videoFrame = cvQueryFrame(capture);
        if (!videoFrame) break;

        // Update model
        cvUpdateBGStatModel(videoFrame, bgModel);

        // Display results
        cvShowImage("FG", bgModel->foreground);
        cvShowImage("BG", bgModel->background);
        cvShowImage("Original", videoFrame);

        // Print frame number:
        if (key == 'f') {
            cout << "Frame: " << frameNr << endl;
            key = ' ';
        }

        // Save images:
        if (key == 's') {
            // string name = string("FG_")+frameNr+".jpg";
            stringstream name;
            name << "output/Frame_" << frameNr << "_FG.jpg";
            cvSaveImage(name.str().c_str(), bgModel->foreground);
            name.str("");
            name << "output/Frame_" << frameNr << "_BG.jpg";
            cvSaveImage(name.str().c_str(), bgModel->background);
            name.str("");
            name << "output/Frame_" << frameNr << "_Original.jpg";
            cvSaveImage(name.str().c_str(), videoFrame);
            cout << "Images saved at frame number " << frameNr << endl;
            key = ' ';
        }

        frameNr++;
        key = cvWaitKey(10);
    }

    cvDestroyWindow("BG");
    cvDestroyWindow("FG");
    cvReleaseBGStatModel(&bgModel);
    cvReleaseCapture(&capture);
    return 0;
}