OpenCV_4.2.0/opencv_contrib-4.2.0/modules/xfeatures2d/samples/pct_webcam.cpp

/*
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/*
Contributed by Gregor Kovalcik <gregor dot kovalcik at gmail dot com>
    based on code provided by Martin Krulis, Jakub Lokoc and Tomas Skopal.

References:
    Martin Krulis, Jakub Lokoc, Tomas Skopal.
    Efficient Extraction of Clustering-Based Feature Signatures Using GPU Architectures.
    Multimedia tools and applications, 75(13), pp.: 8071<37>8103, Springer, ISSN: 1380-7501, 2016

    Christian Beecks, Merih Seran Uysal, Thomas Seidl.
    Signature quadratic form distance.
    In Proceedings of the ACM International Conference on Image and Video Retrieval, pages 438-445.
    ACM, 2010.
*/

#include <opencv2/core.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/xfeatures2d.hpp>

#include <iostream>
#include <string>

using namespace std;
using namespace cv;
using namespace xfeatures2d;


void printHelpMessage(void);
void printHelpMessage(void)
{
    cout << "Example of the PCTSignatures algorithm.\n\n"
        "This program computes and visualizes position-color-texture signatures\n"
        "using images from webcam if available.\n\n"
        "Usage:\n"
        "pct_webcam [sample_count] [seed_count]\n"
        "Note: sample_count must be greater or equal to seed_count.";
}


/** @brief

Example of the PCTSignatures algorithm.

This program computes and visualizes position-color-texture signatures
of images taken from webcam if available.
*/
int main(int argc, char** argv)
{
    // define variables
    Mat frame, signature, result;
    int initSampleCount = 2000;
    int initSeedCount = 400;
    int grayscaleBitsPerPixel = 4;

    // parse for help argument
    {
        for (int i = 1; i < argc; i++)
        {
            if ((string)argv[i] == "-h" || (string)argv[i] == "--help")
            {
                printHelpMessage();
                return 0;
            }
        }
    }

    // parse optional arguments
    if (argc > 1)               // sample count
    {
        initSampleCount = atoi(argv[1]);
        if (initSampleCount <= 0)
        {
            cerr << "Sample count have to be a positive integer: " << argv[1] << endl;
            return 1;
        }
        initSeedCount = (int)floor(static_cast<float>(initSampleCount / 4));
        initSeedCount = std::max(1, initSeedCount);     // fallback if sample count == 1
    }
    if (argc > 2)               // seed count
    {
        initSeedCount = atoi(argv[2]);
        if (initSeedCount <= 0)
        {
            cerr << "Seed count have to be a positive integer: " << argv[2] << endl;
            return 1;
        }
        if (initSeedCount > initSampleCount)
        {
            cerr << "Seed count have to be lower or equal to sample count!" << endl;
            return 1;
        }
    }

    // create algorithm
    Ptr<PCTSignatures> pctSignatures = PCTSignatures::create(initSampleCount, initSeedCount, PCTSignatures::UNIFORM);
    pctSignatures->setGrayscaleBits(grayscaleBitsPerPixel);

    // open video capture device
    VideoCapture videoCapture;
    if (!videoCapture.open(0))
    {
        cerr << "Unable to open the first video capture device with ID = 0!" << endl;
        return 1;
    }

    // Create windows for display.
    namedWindow("Source", WINDOW_AUTOSIZE);
    namedWindow("Result", WINDOW_AUTOSIZE);

    // run drawing loop
    for (;;)
    {
        videoCapture >> frame;
        if (frame.empty()) break; // end of video stream

        pctSignatures->computeSignature(frame, signature);
        PCTSignatures::drawSignature(Mat::zeros(frame.size(), frame.type()), signature, result);

        imshow("Source", frame);                // Show our images inside the windows.
        imshow("Result", result);

        if (waitKey(1) == 27) break;            // stop videocapturing by pressing ESC
    }

    return 0;
}