import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Image;
import java.util.Random;
import javax.swing.BoxLayout;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import org.opencv.core.Core;
import org.opencv.core.Core.MinMaxLocResult;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.highgui.HighGui;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;
class CornerDetector {
private Mat src = new Mat();
private Mat srcGray = new Mat();
private Mat harrisDst = new Mat();
private Mat shiTomasiDst = new Mat();
private Mat harrisCopy = new Mat();
private Mat shiTomasiCopy = new Mat();
private Mat Mc = new Mat();
private JFrame frame;
private JLabel harrisImgLabel;
private JLabel shiTomasiImgLabel;
private static final int MAX_QUALITY_LEVEL = 100;
private int qualityLevel = 50;
private double harrisMinVal;
private double harrisMaxVal;
private double shiTomasiMinVal;
private double shiTomasiMaxVal;
private Random rng = new Random(12345);
public CornerDetector(
String[] args) {
String filename = args.length > 0 ? args[0] :
"../data/building.jpg";
src = Imgcodecs.imread(filename);
if (src.empty()) {
System.err.println("Cannot read image: " + filename);
System.exit(0);
}
Imgproc.cvtColor(src, srcGray, Imgproc.COLOR_BGR2GRAY);
frame = new JFrame("Creating your own corner detector demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Image img = HighGui.toBufferedImage(src);
addComponentsToPane(frame.getContentPane(), img);
frame.pack();
frame.setVisible(true);
int blockSize = 3, apertureSize = 3;
Imgproc.cornerEigenValsAndVecs(srcGray, harrisDst, blockSize, apertureSize);
Mc = Mat.zeros(srcGray.size(), CvType.CV_32F);
float[] harrisData = new float[(int) (harrisDst.total() * harrisDst.channels())];
harrisDst.get(0, 0, harrisData);
float[] McData = new float[(int) (Mc.total() * Mc.channels())];
Mc.get(0, 0, McData);
for( int i = 0; i < srcGray.rows(); i++ ) {
for( int j = 0; j < srcGray.cols(); j++ ) {
float lambda1 = harrisData[(i*srcGray.cols() + j) * 6];
float lambda2 = harrisData[(i*srcGray.cols() + j) * 6 + 1];
McData[i*srcGray.cols()+j] = (float) (lambda1*lambda2 - 0.04f*Math.pow( ( lambda1 + lambda2 ), 2 ));
}
}
Mc.put(0, 0, McData);
MinMaxLocResult res = Core.minMaxLoc(Mc);
harrisMinVal = res.minVal;
harrisMaxVal = res.maxVal;
Imgproc.cornerMinEigenVal(srcGray, shiTomasiDst, blockSize, apertureSize);
res = Core.minMaxLoc(shiTomasiDst);
shiTomasiMinVal = res.minVal;
shiTomasiMaxVal = res.maxVal;
update();
}
private void addComponentsToPane(Container pane, Image img) {
if (!(pane.getLayout() instanceof BorderLayout)) {
pane.add(new JLabel("Container doesn't use BorderLayout!"));
return;
}
JPanel sliderPanel = new JPanel();
sliderPanel.setLayout(new BoxLayout(sliderPanel, BoxLayout.PAGE_AXIS));
sliderPanel.add(new JLabel("Max corners:"));
JSlider slider = new JSlider(0, MAX_QUALITY_LEVEL, qualityLevel);
slider.setMajorTickSpacing(20);
slider.setMinorTickSpacing(10);
slider.setPaintTicks(true);
slider.setPaintLabels(true);
slider.addChangeListener(new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
JSlider source = (JSlider) e.getSource();
qualityLevel = source.getValue();
update();
}
});
sliderPanel.add(slider);
pane.add(sliderPanel, BorderLayout.PAGE_START);
JPanel imgPanel = new JPanel();
harrisImgLabel = new JLabel(new ImageIcon(img));
shiTomasiImgLabel = new JLabel(new ImageIcon(img));
imgPanel.add(harrisImgLabel);
imgPanel.add(shiTomasiImgLabel);
pane.add(imgPanel, BorderLayout.CENTER);
}
private void update() {
int qualityLevelVal = Math.max(qualityLevel, 1);
harrisCopy = src.clone();
float[] McData = new float[(int) (Mc.total() * Mc.channels())];
Mc.get(0, 0, McData);
for (int i = 0; i < srcGray.rows(); i++) {
for (int j = 0; j < srcGray.cols(); j++) {
if (McData[i * srcGray.cols() + j] > harrisMinVal
+ (harrisMaxVal - harrisMinVal) * qualityLevelVal / MAX_QUALITY_LEVEL) {
Imgproc.circle(harrisCopy,
new Point(j, i), 4,
new Scalar(rng.nextInt(256), rng.nextInt(256), rng.nextInt(256)), Imgproc.FILLED);
}
}
}
shiTomasiCopy = src.clone();
float[] shiTomasiData = new float[(int) (shiTomasiDst.total() * shiTomasiDst.channels())];
shiTomasiDst.get(0, 0, shiTomasiData);
for (int i = 0; i < srcGray.rows(); i++) {
for (int j = 0; j < srcGray.cols(); j++) {
if (shiTomasiData[i * srcGray.cols() + j] > shiTomasiMinVal
+ (shiTomasiMaxVal - shiTomasiMinVal) * qualityLevelVal / MAX_QUALITY_LEVEL) {
Imgproc.circle(shiTomasiCopy,
new Point(j, i), 4,
new Scalar(rng.nextInt(256), rng.nextInt(256), rng.nextInt(256)), Imgproc.FILLED);
}
}
}
harrisImgLabel.setIcon(new ImageIcon(HighGui.toBufferedImage(harrisCopy)));
shiTomasiImgLabel.setIcon(new ImageIcon(HighGui.toBufferedImage(shiTomasiCopy)));
frame.repaint();
}
}
public class CornerDetectorDemo {
public static void main(
String[] args) {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new CornerDetector(args);
}
});
}
}