Center of Blob

Author: krutikabapat

CenterofBlob/center_of_multipe_blob.cpp

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+#include "opencv2/highgui/highgui.hpp"
+#include "opencv2/imgproc/imgproc.hpp"
+#include <iostream>
+#include <stdio.h>
+#include <stdlib.h>
+
+using namespace cv;
+using namespace std;
+ 
+RNG rng(12345);
+ 
+void find_moments( Mat src );
+ 
+int main(int argc, char** argv)
+{
+    /// Load source image, convert it to gray
+    Mat src, gray;
+    src = imread(argv[1], 1 );
+    
+    cvtColor( src, gray, COLOR_BGR2GRAY );
+ 
+    namedWindow( "Source", WINDOW_AUTOSIZE );
+    imshow( "Source", src );
+    // call function to find_moments
+    find_moments( gray );
+ 
+    waitKey(0);
+    return(0);
+}
+ 
+void find_moments( Mat gray )
+{
+    Mat canny_output;
+    vector<vector<Point> > contours;
+    vector<Vec4i> hierarchy;
+ 
+    /// Detect edges using canny
+    Canny( gray, canny_output, 50, 150, 3 );
+    // Find contours
+    findContours( canny_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0) );
+ 
+    /// Get the moments
+    vector<Moments> mu(contours.size() );
+    for( int i = 0; i < contours.size(); i++ )
+    { mu[i] = moments( contours[i], false ); }
+ 
+    ///  Get the centroid of figures.
+    vector<Point2f> mc( contours.size() );
+    for( int i = 0; i < contours.size(); i++ )
+    { mc[i] = Point2f( mu[i].m10/mu[i].m00 , mu[i].m01/mu[i].m00 ); }
+    
+ 
+    /// Draw contours
+    
+    Mat drawing(canny_output.size(), CV_8UC3, Scalar(255,255,255));
+
+    for( int i = 0; i< contours.size(); i++ )
+    {
+        Scalar color = Scalar(167,151,0);
+        drawContours( drawing, contours, i, color, 2, 8, hierarchy, 0, Point() );
+        circle( drawing, mc[i], 4, color, -1, 7, 0 );
+    }
+ 
+    /// Show the resultant image
+    namedWindow( "Contours", WINDOW_AUTOSIZE );
+    imshow( "Contours", drawing );
+    waitKey(0);
+		
+}

CenterofBlob/center_of_multiple_blob.py

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+import cv2
+import numpy as np
+import argparse
+
+# create object to pass argument
+arg_parse = argparse.ArgumentParser()
+arg_parse.add_argument("-i", "--ipimage", required=True,
+	help="input image path")
+args = vars(arg_parse.parse_args())
+
+# read image through command line 
+img = cv2.imread(args["ipimage"])
+# convert the image to grayscale
+gray_image = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
+# convert the grayscale image to binary image
+ret,thresh = cv2.threshold(gray_image,127,255,0)
+
+# find contour in the binary image
+im2, contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
+for c in contours:
+	# calculate moments for each contour
+	M = cv2.moments(c)
+	cX = int(M["m10"] / M["m00"])
+	cY = int(M["m01"] / M["m00"])
+	
+	
+    # calculate x,y coordinate of center
+	cv2.circle(img, (cX, cY), 5, (255, 255, 255), -1)
+	cv2.putText(img, "centroid", (cX - 25, cY - 25),cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 2)
+	# display the image
+	cv2.imshow("Image", img)
+	cv2.waitKey(0)
+
+# 3.4.1 im2, contours, hierarchy = cv.findContours(thresh, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE)
+# 3.2.0 im2, contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE) 	
+
+

CenterofBlob/single_blob.cpp

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+// declare Mat variables, thr, gray and src
+Mat thr, gray, src;
+ 
+// convert image to grayscale
+cvtColor( src, gray, COLOR_BGR2GRAY );
+ 
+// convert grayscale to binary image
+threshold( gray, thr, 100,255,THRESH_BINARY );
+ 
+// find moments of the image
+Moments m = moments(thr,true);
+Point p(m.m10/m.m00, m.m01/m.m00);
+ 
+// coordinates of centroid
+cout<< Mat(p)<< endl;
+ 
+// show the image with a point mark at the centroid
+circle(src, p, 5, Scalar(128,0,0), -1);
+imshow("Image with center",src);
+waitKey(0);

CenterofBlob/single_blob.py

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+# convert image to grayscale image
+gray_image = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
+ 
+# convert the grayscale image to binary image
+ret,thresh = cv2.threshold(gray_image,127,255,0)
+ 
+# calculate moments of binary image
+M = cv2.moments(thresh)
+ 
+# calculate x,y coordinate of center
+cX = int(M["m10"] / M["m00"])
+cY = int(M["m01"] / M["m00"])
+ 
+# put text and highlight the center
+cv2.circle(img, (cX, cY), 5, (255, 255, 255), -1)
+cv2.putText(img, "centroid", (cX - 25, cY - 25),cv2.FONT_HERSHEY_SIMPLEX, 0.5, (255, 255, 255), 2)
+ 
+# display the image
+cv2.imshow("Image", img)
+cv2.waitKey(0)