Hello..
I am implementing a java program that highlights the difference between two images.
I used the following steps :
- turning the images into gray scale
- apply feature detection to the images in order to check if they are similar
- applying absdiff to them
- highlighting the difference in the original picture
My problem is : when I upload two images that are similar but one of them have outliers, or the position is slightly different , the whole image become different
the code is : ` package image;
import org.opencv.calib3d.Calib3d;
import org.opencv.core.*;
import org.opencv.features2d.*;
import org.opencv.features2d.DMatch;
import org.opencv.features2d.KeyPoint;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.Vector;
import javax.imageio.ImageIO;
import javax.swing.JOptionPane;
public class SURFDetector22 {
boolean answer;
//copy matrix
public static Mat imitate(Mat m){
return new Mat(m.height(), m.width(), m.type());
}
//draw rect
public static void drawRotatedRect(Mat image, RotatedRect rotatedRect, Scalar color, int thickness) {
Point[] vertices = new Point[4];
rotatedRect.points(vertices);
MatOfPoint points = new MatOfPoint(vertices);
Imgproc.drawContours(image, Arrays.asList(points), -1, color, thickness);
}
//diff btw matrices
public static Mat diff(Mat mat1, Mat mat2){
Mat dst = imitate(mat1);
Core.absdiff(mat1, mat2, dst);
return dst;}
public void imageComparison(File file1, File file2) throws IOException {
File lib = null;
String os = System.getProperty("os.name");
String bitness = System.getProperty("sun.arch.data.model");
if (os.toUpperCase().contains("WINDOWS")) {
if (bitness.endsWith("64")) {
lib = new File("libs//x64//" + System.mapLibraryName("opencv_java2411"));
} else {
lib = new File("libs//x86//" + System.mapLibraryName("opencv_java2411"));
}
}
System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
///////step 1 : read images
///first image
String bookObject = file1.getAbsolutePath();
Mat objectImage = Highgui.imread(bookObject, Highgui.CV_LOAD_IMAGE_COLOR);
Mat mat1 = new Mat(objectImage.height(),objectImage.width(),CvType.CV_8UC1);
Imgproc.cvtColor(objectImage, mat1, Imgproc.COLOR_RGB2GRAY);
byte[] data1 = new byte[mat1.rows() * mat1.cols() * (int)(mat1.elemSize())];
mat1.get(0, 0, data1);
BufferedImage image1 = new BufferedImage(mat1.cols(),mat1.rows(), BufferedImage.TYPE_BYTE_GRAY);
image1.getRaster().setDataElements(0, 0, mat1.cols(), mat1.rows(), data1);
File ouptut = new File("gray//1.jpg");
ImageIO.write(image1, "jpg", ouptut);
//bade a3ml show la hyde el sora
//2nd image
String bookScene = file2.getAbsolutePath();
Mat sceneImage = Highgui.imread(bookScene, Highgui.CV_LOAD_IMAGE_COLOR);
Mat mat2 = new Mat(sceneImage.height(),sceneImage.width(),CvType.CV_8UC1);
Imgproc.cvtColor(sceneImage, mat2, Imgproc.COLOR_RGB2GRAY );
byte[] data2 = new byte[mat2.rows() * mat2.cols() * (int)(mat2.elemSize())];
mat2.get(0, 0, data2);
BufferedImage image2 = new BufferedImage(mat2.cols(),mat2.rows(), BufferedImage.TYPE_BYTE_GRAY);
image2.getRaster().setDataElements(0, 0, mat2.cols(), mat2.rows(), data2);
File ouptut2 = new File("gray//2.jpg");
ImageIO.write(image2, "jpg", ouptut2);
//////step 2 : Detect and extract features
MatOfKeyPoint objectKeyPoints = new MatOfKeyPoint();
FeatureDetector featureDetector = FeatureDetector.create(FeatureDetector.SURF);
System.out.println("Detecting key points...");
featureDetector.detect(mat1, objectKeyPoints);
System.out.println("----- key pointss image 1----" + objectKeyPoints);
//KeyPoint[] keypoints = objectKeyPoints.toArray();
System.out.println(objectKeyPoints);
MatOfKeyPoint objectDescriptors = new MatOfKeyPoint();
DescriptorExtractor descriptorExtractor = DescriptorExtractor.create(DescriptorExtractor.SURF);
System.out.println("Computing descriptors...");
descriptorExtractor.compute(objectImage, objectKeyPoints, objectDescriptors);
// Create the matrix for output image.
Mat outputImage = new Mat(objectImage.rows(), objectImage.cols(), Highgui.CV_LOAD_IMAGE_COLOR);
Scalar newKeypointColor = new Scalar(255, 0, 0);
System.out.println("Drawing key points on object image...");
Features2d.drawKeypoints(objectImage, objectKeyPoints, outputImage, newKeypointColor, 0);
// Match object image with the scene image
MatOfKeyPoint sceneKeyPoints = new MatOfKeyPoint();
MatOfKeyPoint sceneDescriptors = new MatOfKeyPoint();
System.out.println("Detecting key points in background image...");
featureDetector.detect(mat2, sceneKeyPoints);
System.out.println("----img2 key pointys----" + sceneKeyPoints);
System.out.println("Computing descriptors in background image...");
descriptorExtractor.compute(mat2, sceneKeyPoints, sceneDescriptors);
Mat matchoutput = new Mat(mat2.rows() * 2, mat2.cols() * 2, Highgui.CV_LOAD_IMAGE_COLOR);
Scalar matchestColor = new Scalar(0, 255, 0);
List<MatOfDMatch> matches = new LinkedList<MatOfDMatch>();
DescriptorMatcher descriptorMatcher = DescriptorMatcher.create(DescriptorMatcher.FLANNBASED);
System.out.println("Matching object and scene images...");
descriptorMatcher.knnMatch(objectDescriptors, sceneDescriptors, matches, 2);
System.out.println("Calculating good match list...");
LinkedList<DMatch> goodMatchesList = new LinkedList<DMatch>();
float nndrRatio = 0.7f;
for (int i = 0; i < matches.size(); i++) {
MatOfDMatch matofDMatch = matches.get(i);
DMatch[] dmatcharray = matofDMatch.toArray();
DMatch m1 = dmatcharray[0];
DMatch m2 = dmatcharray[1];
if (m1.distance <= m2.distance * nndrRatio) {
goodMatchesList.addLast(m1);
}
}
if (goodMatchesList.size() >= matches.size() - 1) {
System.out.println("Object Found!!!");
answer = true;
List<KeyPoint> objKeypointlist = objectKeyPoints.toList();
List<KeyPoint> scnKeypointlist = sceneKeyPoints.toList();
LinkedList<Point> objectPoints = new LinkedList<>();
LinkedList<Point> scenePoints = new LinkedList<>();
for (int i = 0; i < goodMatchesList.size(); i++) {
objectPoints.addLast(objKeypointlist.get(goodMatchesList.get(i).queryIdx).pt);
scenePoints.addLast(scnKeypointlist.get(goodMatchesList.get(i).trainIdx).pt);
}
MatOfPoint2f objMatOfPoint2f = new MatOfPoint2f();
objMatOfPoint2f.fromList(objectPoints);
MatOfPoint2f scnMatOfPoint2f = new MatOfPoint2f();
scnMatOfPoint2f.fromList(scenePoints);
Mat homography = Calib3d.findHomography(objMatOfPoint2f, scnMatOfPoint2f, Calib3d.RANSAC, 3);
Mat obj_corners = new Mat(4, 1, CvType.CV_32FC2);
Mat scene_corners = new Mat(4, 1, CvType.CV_32FC2);
obj_corners.put(0, 0, new double[] { 0, 0 });
obj_corners.put(1, 0, new double[] { objectImage.cols(), 0 });
obj_corners.put(2, 0, new double[] { objectImage.cols(), objectImage.rows() });
obj_corners.put(3, 0, new double[] { 0, objectImage.rows() });
System.out.println("Transforming object corners to scene corners...");
Core.perspectiveTransform(obj_corners, scene_corners, homography);
Mat img = Highgui.imread(bookScene, Highgui.CV_LOAD_IMAGE_COLOR);
Core.line(img, new Point(scene_corners.get(0, 0)), new Point(scene_corners.get(1, 0)),
new Scalar(0, 255, 0), 4);
Core.line(img, new Point(scene_corners.get(1, 0)), new Point(scene_corners.get(2, 0)),
new Scalar(0, 255, 0), 4);
Core.line(img, new Point(scene_corners.get(2, 0)), new Point(scene_corners.get(3, 0)),
new Scalar(0, 255, 0), 4);
Core.line(img, new Point(scene_corners.get(3, 0)), new Point(scene_corners.get(0, 0)),
new Scalar(0, 255, 0), 4);
System.out.println("Drawing matches image...");
MatOfDMatch goodMatches = new MatOfDMatch();
goodMatches.fromList(goodMatchesList);
Features2d.drawMatches(objectImage, objectKeyPoints, sceneImage, sceneKeyPoints, goodMatches, matchoutput,
matchestColor, newKeypointColor, new MatOfByte(), 2);
// Highgui.imwrite("output//outputImage.jpg", outputImage);
// Highgui.imwrite("output//matchoutput.jpg", matchoutput);
// Highgui.imwrite("output//img.jpg", img);
// File f= new File("output");
Highgui.imwrite("output//1.jpg", outputImage);
Highgui.imwrite("output//2.jpg", matchoutput);
Highgui.imwrite("output//3.jpg", img);
} else {
System.out.println("Object Not Found");
answer = false;
Mat res = diff(mat1,mat2);
byte[] data3 = new byte[res.rows() * res.cols() * (int)(res.elemSize())];
res.get(0, 0, data3);
BufferedImage image3 = new BufferedImage(res.cols(),res.rows(), BufferedImage.TYPE_BYTE_GRAY);
image3.getRaster().setDataElements(0, 0, res.cols(), res.rows(), data3);
File ouptut3 = new File("gray//3.jpg");
ImageIO.write(image3, "jpg", ouptut3);
////////////////////////////
List <MatOfPoint> contours = new ArrayList<>();
Mat dest = Mat.zeros(res.size(), CvType.CV_8UC3);
Scalar white = new Scalar(255, 255, 255);
// Find contours
Imgproc.findContours(res, contours, new Mat(), Imgproc.RETR_EXTERNAL, Imgproc.CHAIN_APPROX_SIMPLE);
Scalar green = new Scalar(81, 190, 0);
for (MatOfPoint contour: contours) {
RotatedRect rotatedRect = Imgproc.minAreaRect(new MatOfPoint2f(contour.toArray()));
drawRotatedRect(mat1, rotatedRect, green, 4);
}
byte[] data4 = new byte[mat1.rows() * mat1.cols() * (int)(mat1.elemSize())];
mat1.get(0, 0, data4);
BufferedImage image4 = new BufferedImage(mat1.cols(),mat1.rows(), BufferedImage.TYPE_BYTE_GRAY);
image3.getRaster().setDataElements(0, 0, mat1.cols(), mat1.rows(), data4);
File ouptut4 = new File("gray//4.jpg");
ImageIO.write(image4, "jpg", ouptut4);
/////////////////
}
System.out.println("Ended....");
}
}
`