usefull.detectContours.java Source code

Introduction

Here is the source code for usefull.detectContours.java

Source

package usefull;

//********************************************************

//Example : computer the difference between a pair of images,
//detect the resulting contours and display them

//Author : Toby Breckon, toby.breckon@durham.ac.uk

//Copyright (c) 2015 Durham University
//License : LGPL - http://www.gnu.org/licenses/lgpl.html

//********************************************************

//import required Java components

import java.util.List;
import java.util.Vector;

//import required OpenCV components

import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Size;
import org.opencv.core.Scalar;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;

//********************************************************

public class detectContours {

    public static void main(String[] args) throws InterruptedException {

        // load the Core OpenCV library by name

        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        // load two image files

        Mat img1 = Highgui.imread("files/cctv_example1.png");
        Mat img2 = Highgui.imread("files/cctv_example2.png");

        // create a new image object to store image difference

        Mat diff_img = new Mat();

        // compute the difference between the images

        Core.absdiff(img1, img2, diff_img);

        // now convert it to grey and threshold it

        Mat grey = new Mat();
        Imgproc.cvtColor(diff_img, grey, Imgproc.COLOR_BGR2GRAY);

        Imgproc.adaptiveThreshold(grey, diff_img, 255, Imgproc.ADAPTIVE_THRESH_MEAN_C, Imgproc.THRESH_BINARY_INV, 7,
                10);

        // now clean it up using some morphological operations

        Size ksize = new Size(15, 15);
        Mat kernel = Imgproc.getStructuringElement(Imgproc.MORPH_ELLIPSE, ksize);

        Imgproc.morphologyEx(diff_img, diff_img, Imgproc.MORPH_CLOSE, kernel);

        // find the all the contours from the binary image using the edge to contour
        // stuff we looked at in lectures

        List<MatOfPoint> contours = new Vector<MatOfPoint>();

        Imgproc.findContours(diff_img, contours, new Mat(), Imgproc.RETR_LIST, Imgproc.CHAIN_APPROX_SIMPLE);

        // draw the contours on image 2 in red

        Imgproc.drawContours(img2, contours, -1, new Scalar(0, 0, 255));

        // find the largest contour by area 

        double maxArea = 0;
        int maxAreaIndex = 0;

        for (int i = 0; i < contours.size(); i++) {

            double area = Imgproc.contourArea(contours.get(i), false);

            if (area > maxArea) {
                maxArea = area;
                maxAreaIndex = i;
            }
        }

        // draw the largest contour in red

        Imgproc.drawContours(img2, contours, maxAreaIndex, new Scalar(0, 255, 0));

        // create a new window objects

        Imshow ims1 = new Imshow("Image 1");
        Imshow ims2 = new Imshow("Image 2");
        Imshow ims_diff = new Imshow("Difference");

        // display images

        ims1.showImage(img1);
        ims2.showImage(img2);
        ims_diff.showImage(diff_img);

    }
}

//********************************************************