Desktop : OpenCV Pencil Sketch

<h5>Goal</h5>
Test OpenCV pencil sketch.

```OpenCV_PencilSketch.java
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.photo.Photo;

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

public class OpenCV_PencilSketch {
    static{ System.loadLibrary(Core.NATIVE_LIBRARY_NAME); }
    private JFrame frmjavaSwing;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    OpenCV_PencilSketch window = new OpenCV_PencilSketch();
                    window.frmjavaSwing.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public OpenCV_PencilSketch() {
        initialize();

    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        final Mat source = Imgcodecs.imread("D:\\projects\\Java\\OpenCV_Samples\\resource\\imgs\\DSC_0704.jpg");

        BufferedImage image=matToBufferedImage(source);

        frmjavaSwing = new JFrame();
        frmjavaSwing.setTitle("opencv pencilSketch 處理練習");
        frmjavaSwing.setBounds(100, 100, 703, 601);
        frmjavaSwing.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmjavaSwing.getContentPane().setLayout(null);

        final JLabel showShadeFactorValue = new JLabel("0.01");
        showShadeFactorValue.setBounds(83, 53, 46, 15);
        frmjavaSwing.getContentPane().add(showShadeFactorValue);

        final JLabel showSigmaSValue = new JLabel("1");
        showSigmaSValue.setBounds(258, 43, 46, 15);
        frmjavaSwing.getContentPane().add(showSigmaSValue);

        final JLabel lblNewLabel = new JLabel("");
        lblNewLabel.setBounds(10, 68, 322, 474);
        lblNewLabel.setIcon(new ImageIcon(image));
        frmjavaSwing.getContentPane().add(lblNewLabel);

        final JSlider slider_sigmaS = new JSlider();
        slider_sigmaS.setMinimum(1);
        slider_sigmaS.setValue(1);
        slider_sigmaS.setMaximum(200);
        slider_sigmaS.setBounds(229, 10, 75, 25);
        frmjavaSwing.getContentPane().add(slider_sigmaS);

        final JSlider slider_shadeFactor = new JSlider();
        slider_shadeFactor.setMinimum(1);
        slider_shadeFactor.setMaximum(17);
        slider_shadeFactor.setValue(1);

        slider_shadeFactor.setBounds(46, 22, 86, 25);
        frmjavaSwing.getContentPane().add(slider_shadeFactor);

        JLabel lblAlpha = new JLabel("shade_factor ");
        lblAlpha.setBounds(51, 10, 95, 15);
        frmjavaSwing.getContentPane().add(lblAlpha);

        JLabel lblsigma_s = new JLabel("sigma_s");
        lblsigma_s.setBounds(171, 10, 67, 15);
        frmjavaSwing.getContentPane().add(lblsigma_s);

        JLabel lblNewLabel_1 = new JLabel("sigma_r");
        lblNewLabel_1.setBounds(363, 10, 85, 15);
        frmjavaSwing.getContentPane().add(lblNewLabel_1);

        final JSlider slider_sigmaR = new JSlider();

        slider_sigmaR.setValue(1);
        slider_sigmaR.setMinimum(1);
        slider_sigmaR.setMaximum(30);
        slider_sigmaR.setBounds(415, 10, 75, 25);
        frmjavaSwing.getContentPane().add(slider_sigmaR);

        final JLabel showSigmaRValue = new JLabel("1");
        showSigmaRValue.setBounds(438, 43, 46, 15);
        frmjavaSwing.getContentPane().add(showSigmaRValue);

        final JLabel label = new JLabel("");
        label.setBounds(363, 68, 322, 474);
        frmjavaSwing.getContentPane().add(label);

        slider_sigmaR.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent arg0) {
                showSigmaRValue.setText((float)slider_sigmaR.getValue()/10+"");

                Mat[] temp=new Mat[2];
                temp=(PencilSketch(slider_sigmaS.getValue(),(float)slider_sigmaR.getValue()/10,(float)slider_shadeFactor.getValue()/100));
                BufferedImage tmp1=matToBufferedImage(temp[0]);
                BufferedImage tmp2=matToBufferedImage(temp[1]);
                lblNewLabel.setIcon(new ImageIcon(tmp1));
                label.setIcon(new ImageIcon(tmp2));
            }
        });
        slider_shadeFactor.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent arg0) {
                //System.out.println(slider_alpha.getValue());
                showShadeFactorValue.setText((float)slider_shadeFactor.getValue()/100+"");
                Mat[] temp=new Mat[2];
                temp=(PencilSketch(slider_sigmaS.getValue(),(float)slider_sigmaR.getValue()/10,(float)slider_shadeFactor.getValue()/100));
                BufferedImage tmp1=matToBufferedImage(temp[0]);
                BufferedImage tmp2=matToBufferedImage(temp[1]);
                lblNewLabel.setIcon(new ImageIcon(tmp1));
                label.setIcon(new ImageIcon(tmp2));
            }
        });

        slider_sigmaS.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent arg0) {
                showSigmaSValue.setText(slider_sigmaS.getValue()+"");
                Mat[] temp=new Mat[2];
                temp=(PencilSketch(slider_sigmaS.getValue(),(float)slider_sigmaR.getValue()/10,(float)slider_shadeFactor.getValue()/100));
                BufferedImage tmp1=matToBufferedImage(temp[0]);
                BufferedImage tmp2=matToBufferedImage(temp[1]);
                lblNewLabel.setIcon(new ImageIcon(tmp1));
                label.setIcon(new ImageIcon(tmp2));
            }
        });
    }
    public Mat[] PencilSketch(float sigma_s ,float sigma_r,float shade_factor){
        Mat[] output=new Mat[2];
        Mat src = Imgcodecs.imread("D:\\projects\\Java\\OpenCV_Samples\\resource\\imgs\\DSC_0704.jpg",Imgcodecs.CV_LOAD_IMAGE_COLOR);
        Mat dst2=new Mat();
        Mat dst1=new Mat();
        Photo.pencilSketch(src, dst1, dst2, sigma_s, sigma_r, shade_factor);
        output[0]=dst1;
        output[1]=dst2;
        return output;
    }

    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_pencil_sketch.JPG](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/276243/735ad102-5eca-3efc-50c7-915a0c3574b7.jpeg)