samples/cpp/connected_components.cpp


This program demonstrates connected components and use of the trackbar

#include <iostream>
using namespace cv ;
using namespace std ;
Mat img;
int threshval = 100;
static void on_trackbar( int , void *)
{
Mat bw = threshval < 128 ? (img < threshval) : (img > threshval);
Mat labelImage(img. size (), CV_32S );
int nLabels = connectedComponents (bw, labelImage, 8);
std::vector<Vec3b> colors(nLabels);
colors[0] = Vec3b (0, 0, 0); //background
for ( int label = 1; label < nLabels; ++label){
colors[label] = Vec3b ( (rand()&255), (rand()&255), (rand()&255) );
}
Mat dst(img. size (), CV_8UC3 );
for ( int r = 0; r < dst.rows; ++r){
for ( int c = 0; c < dst.cols; ++c){
int label = labelImage. at < int >(r, c);
Vec3b &pixel = dst.at< Vec3b >(r, c);
pixel = colors[label];
}
}
imshow ( "Connected Components" , dst );
}
int main( int argc, const char ** argv )
{
CommandLineParser parser(argc, argv, "{@image|stuff.jpg|image for converting to a grayscale}" );
parser. about ( "\nThis program demonstrates connected components and use of the trackbar\n" );
parser. printMessage ();
cout << "\nThe image is converted to grayscale and displayed, another image has a trackbar\n"
"that controls thresholding and thereby the extracted contours which are drawn in color\n" ;
字符串 inputImage = parser. get < string >(0);
if (img.empty())
{
cout << "Could not read input image file: " << inputImage << endl;
return EXIT_FAILURE;
}
imshow ( "Image" , img );
namedWindow ( "Connected Components" , WINDOW_AUTOSIZE );
createTrackbar ( "Threshold" , "Connected Components" , &threshval, 255, on_trackbar );
on_trackbar(threshval, 0);
return EXIT_SUCCESS;
}