/src/Blobs.java

import java.awt.image.BufferedImage;

import static com.googlecode.javacv.cpp.opencv_core.*;

import static com.googlecode.javacv.cpp.opencv_imgproc.*;

import static com.googlecode.javacv.cpp.opencv_highgui.*;

import java.io.File;

import java.io.IOException;

import java.util.ArrayList;

import javax.imageio.ImageIO;

import com.googlecode.javacpp.Loader;

import com.googlecode.javacv.cpp.opencv_core.CvPoint;

import com.googlecode.javacv.cpp.opencv_core.CvPoint2D32f;

import com.googlecode.javacv.cpp.opencv_core.CvScalar;

import com.googlecode.javacv.cpp.opencv_core.IplImage;

import com.googlecode.javacv.cpp.opencv_imgproc;





public class Blobs {

	

	public static void main(String[] args) throws IOException

	{

		File file1 = new File("before.jpg");

		File file2 = new File("after.jpg");

		

		BufferedImage bimage1 = ImageIO.read(file1);

		IplImage before = IplImage.createFrom(bimage1);

		

		BufferedImage bimage2 = ImageIO.read(file2);

		IplImage after = IplImage.createFrom(bimage2);

		

		

		IplImage diff = IplImage.createCompatible(before);

		

		IplImage src = cvLoadImage("example.jpg");

		cvAbsDiff(before, after, diff);



		IplImage diffg = IplImage.create(cvGetSize(before),8,1);

		opencv_imgproc.cvCvtColor(diff, diffg, CV_RGB2GRAY);



		// thresholding (keep only pixels whose difference is larger than 50

		cvThreshold(diffg, diffg, 200, 255, CV_THRESH_BINARY);			



		// find connected components

		final ArrayList<CvRect> blobs =  detectBlobs(diffg);		

			

		for (CvRect blob : blobs)

		{

			System.out.println("location of this blob:" + blob.x() + "," + blob.y()+","+blob.width()+","+blob.height());

			CvPoint center = cvPointFrom32f(new CvPoint2D32f(blob.x(),blob.y()));			

			cvCircle(src, center, 1, CvScalar.RED, 6, CV_AA, 0);   

			

		}

		cvSaveImage("look.jpg", src);

		cvShowImage("Result",src);  

		cvWaitKey(0);

	}





	public static ArrayList<CvRect> detectBlobs(IplImage input)

	{

			IplImage clone = input.clone();

			CvMemStorage storage = CvMemStorage.create();

			CvSeq contour = new CvSeq(null);

			cvFindContours(clone, storage, contour, Loader.sizeof(CvContour.class), CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);



			ArrayList<CvRect> rects = new ArrayList<CvRect>(); 



			while (contour != null && !contour.isNull())

			{

				if (contour.elem_size() > 0) {

					CvRect boundingRect = cvBoundingRect(contour,0);

					rects.add(boundingRect);

				}

				contour = contour.h_next();

			}

			return rects;

		}



	



}