Desktop : OpenCV Sobel Filter2 

<h5>Goal</h5>
Test OpenCV sobel filter.

```OpenCV_Sobel_Filter2.java
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;
import java.awt.image.BufferedImage;

public class OpenCV_Sobel_Filter2 {

    static {System.loadLibrary(Core.NATIVE_LIBRARY_NAME);}
    private JFrame frmjavaSwing;

    /**
        * Launch the application.
        */
    public static void main(String[] argv){
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try{
                    OpenCV_Sobel_Filter2 window = new OpenCV_Sobel_Filter2();
                    window.frmjavaSwing.setVisible(true);
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        });
    }

    /**
        * Create the application.
        */
    public OpenCV_Sobel_Filter2(){
        init();
    }

    /**
        * Init the contents of the frame.
        */
    private void init(){
        final Mat src = Imgcodecs.imread(
                "D:\\projects\\Java\\OpenCV_Samples\\resource\\imgs\\lena.jpg");
        BufferedImage image = matToBufferedImage(src);

        frmjavaSwing = new JFrame();
        frmjavaSwing.setTitle("opencv Sobel API½m²ß1");
        frmjavaSwing.setBounds(100, 100, 560, 620);
        frmjavaSwing.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmjavaSwing.getContentPane().setLayout(null);

        final JLabel lblNewLabel = new JLabel("");
        lblNewLabel.setBounds(5, 60, image.getHeight()+10, image.getWidth()+10);
        lblNewLabel.setIcon(new ImageIcon(image));
        frmjavaSwing.getContentPane().add(lblNewLabel);

        JLabel lblKsize = new JLabel("dx");
        lblKsize.setBounds(10, 10, 46, 15);
        frmjavaSwing.getContentPane().add(lblKsize);

        final JSlider slider_dx = new JSlider();
        slider_dx.setMaximum(2);

        slider_dx.setValue(1);
        slider_dx.setBounds(50, 0, 200, 25);
        frmjavaSwing.getContentPane().add(slider_dx);

        final JLabel lblKsize_Val = new JLabel("1");
        lblKsize_Val.setBounds(253, 10, 46, 15);
        frmjavaSwing.getContentPane().add(lblKsize_Val);

        JLabel lblScale = new JLabel(" dy");
        lblScale.setBounds(5, 35, 27, 15);
        frmjavaSwing.getContentPane().add(lblScale);

        final JSlider slider_dy = new JSlider();
        slider_dy.setMaximum(2);

        slider_dy.setValue(1);
        slider_dy.setBounds(50, 35, 200, 25);
        frmjavaSwing.getContentPane().add(slider_dy);

        final JLabel lblScale_Val = new JLabel("1");
        lblScale_Val.setBounds(253, 35, 46, 15);
        frmjavaSwing.getContentPane().add(lblScale_Val);

        slider_dx.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent arg0) {

                lblKsize_Val.setText(slider_dx.getValue()+"");
                BufferedImage newImage=matToBufferedImage(Sobel(src,slider_dx.getValue(),slider_dy.getValue()));
                lblNewLabel.setIcon(new ImageIcon(newImage));
            }
        });

        slider_dy.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent arg0) {
                lblScale_Val.setText(slider_dy.getValue()+"");
                BufferedImage newImage=matToBufferedImage(Sobel(src,slider_dx.getValue(),slider_dy.getValue()));
                lblNewLabel.setIcon(new ImageIcon(newImage));

            }
        });
    }
    public Mat Sobel(Mat source,int dx,int dy){
        Mat destination=new Mat(source.rows(),source.cols(),source.type());
        if((dx==0)&&(dy==0)){
            dx=1;
        }
        Imgproc.Sobel(source, destination, -1,dx,dy);
        return destination;

    }

    public BufferedImage matToBufferedImage(Mat matrix) {
        int cols = matrix.cols();
        int rows = matrix.rows();
        int elemSize = (int)matrix.elemSize();
        byte[] data = new byte[cols * rows * elemSize];
        int type;
        matrix.get(0, 0, data);
        switch (matrix.channels()) {
            case 1:
                type = BufferedImage.TYPE_BYTE_GRAY;
                break;
            case 3:
                type = BufferedImage.TYPE_3BYTE_BGR;
                // bgr to rgb
                byte b;
                for(int i=0; i<data.length; i=i+3) {
                    b = data[i];
                    data[i] = data[i+2];
                    data[i+2] = b;
                }
                break;
            default:
                return null;
        }
        BufferedImage image2 = new BufferedImage(cols, rows, type);
        image2.getRaster().setDataElements(0, 0, cols, rows, data);
        return image2;
    }
}
```
<h5>Result</h5>
![opencv_sobel_filter2.JPG](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/276243/4eee741b-7ea3-f98a-8e4b-f60afce4f616.jpeg)