09_canny_edge_detector.cpp

//
// Created by varora on 22/04/24.
//
#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"
#include <iostream>

using namespace cv;

Mat src, src_gray;
Mat dst, detected_edges;

int lowThreshold = 0;
const int max_lowThreshold = 100;
const int ratio = 3;
const int kernel_size = 3;
const char* window_name = "Edge Map";

static void CannyThreshold(int, void*)
{
    lowThreshold = getTrackbarPos( "Min Threshold:", window_name );

    blur( src_gray, detected_edges, Size(3,3) );

    Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );

    dst = Scalar::all(0);

    src.copyTo( dst, detected_edges);

    imshow( window_name, dst );
}


int main( int argc, char** argv )
{
    CommandLineParser parser( argc, argv, "{@input | ims/sample.jpg | input image}" );
    src = imread( samples::findFile( parser.get<String>( "@input" ) ), IMREAD_COLOR ); // Load an image

    if( src.empty() )
    {
        std::cout << "Could not open or find the image!\n" << std::endl;
        std::cout << "Usage: " << argv[0] << " <Input image>" << std::endl;
        return -1;
    }

    dst.create( src.size(), src.type() );

    cvtColor( src, src_gray, COLOR_BGR2GRAY );

    namedWindow( window_name, WINDOW_AUTOSIZE );

    createTrackbar( "Min Threshold:", window_name, NULL, max_lowThreshold, CannyThreshold );

    CannyThreshold(0, 0);

    waitKey(0);

    return 0;
}