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/**
* Count and segment overlapping objects with Watershed and Distance Transform.
*
* See the tutorial at:
* http://opencv-code.com/count-and-segment-overlapping-objects-with-watershed-and-distance-transform/
*/
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
int main()
{
cv::Mat src = cv::imread("coins.jpg");
if (!src.data)
return -1;
cv::imshow("src", src);
// Create binary image from source image
cv::Mat bw;
cv::cvtColor(src, bw, CV_BGR2GRAY);
cv::threshold(bw, bw, 40, 255, CV_THRESH_BINARY);
cv::imshow("bw", bw);
// Perform the distance transform algorithm
cv::Mat dist;
cv::distanceTransform(bw, dist, CV_DIST_L2, 3);
// Normalize the distance image for range = {0.0, 1.0}
// so we can visualize and threshold it
cv::normalize(dist, dist, 0, 1., cv::NORM_MINMAX);
cv::imshow("dist", dist);
// Threshold to obtain the peaks
// This will be the markers for the foreground objects
cv::threshold(dist, dist, .5, 1., CV_THRESH_BINARY);
cv::imshow("dist2", dist);
// Create the CV_8U version of the distance image
// It is needed for cv::findContours()
cv::Mat dist_8u;
dist.convertTo(dist_8u, CV_8U);
// Find total markers
std::vector<std::vector<cv::Point> > contours;
cv::findContours(dist_8u, contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
int ncomp = contours.size();
// Create the marker image for the watershed algorithm
cv::Mat markers = cv::Mat::zeros(dist.size(), CV_32SC1);
// Draw the foreground markers
for (int i = 0; i < ncomp; i++)
cv::drawContours(markers, contours, i, cv::Scalar::all(i+1), -1);
// Draw the background marker
cv::circle(markers, cv::Point(5,5), 3, CV_RGB(255,255,255), -1);
cv::imshow("markers", markers*10000);
// Perform the watershed algorithm
cv::watershed(src, markers);
// Generate random colors
std::vector<cv::Vec3b> colors;
for (int i = 0; i < ncomp; i++)
{
int b = cv::theRNG().uniform(0, 255);
int g = cv::theRNG().uniform(0, 255);
int r = cv::theRNG().uniform(0, 255);
colors.push_back(cv::Vec3b((uchar)b, (uchar)g, (uchar)r));
}
// Create the result image
cv::Mat dst = cv::Mat::zeros(markers.size(), CV_8UC3);
// Fill labeled objects with random colors
for (int i = 0; i < markers.rows; i++)
{
for (int j = 0; j < markers.cols; j++)
{
int index = markers.at<int>(i,j);
if (index > 0 && index <= ncomp)
dst.at<cv::Vec3b>(i,j) = colors[index-1];
else
dst.at<cv::Vec3b>(i,j) = cv::Vec3b(0,0,0);
}
}
cv::imshow("dst", dst);
cv::waitKey(0);
return 0;
}
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