Desktop : OpenCV Mean Filter

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

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

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

public class OpenCV_MeanFilter {

    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_MeanFilter window = new OpenCV_MeanFilter();
                    window.frmjavaSwing.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

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

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

        BufferedImage image=matToBufferedImage(source);

        frmjavaSwing = new JFrame();
        frmjavaSwing.setTitle("opencv 均值濾波器練習");
        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);

        JButton btn3 = new JButton("Kernel-Size3");
        btn3.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                BufferedImage newImage=matToBufferedImage(Convolution(source,3));
                lblNewLabel.setIcon(new ImageIcon(newImage));
            }
        });
        btn3.setBounds(10, 10, 114, 23);
        frmjavaSwing.getContentPane().add(btn3);

        JButton btnNewButton = new JButton("Kernel-Size7");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                BufferedImage newImage=matToBufferedImage(Convolution(source,7));
                lblNewLabel.setIcon(new ImageIcon(newImage));
            }
        });
        btnNewButton.setBounds(162, 10, 114, 23);
        frmjavaSwing.getContentPane().add(btnNewButton);

        JButton btn9 = new JButton("Kernel-Size9");
        btn9.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                BufferedImage newImage=matToBufferedImage(Convolution(source,9));
                lblNewLabel.setIcon(new ImageIcon(newImage));
            }
        });
        btn9.setBounds(316, 10, 114, 23);
        frmjavaSwing.getContentPane().add(btn9);
    }

    public Mat Convolution(Mat source,int kernelSize){
        Mat kernel = Mat.ones(kernelSize,kernelSize, CvType.CV_32F);
        for(int i=0; i<kernel.rows(); i++){
            for(int j=0; j<kernel.cols(); j++){

                double[] tmp = kernel.get(i, j);
                tmp[0]=tmp[0]/(kernelSize * kernelSize);
                kernel.put(i,j, tmp);
            }
        }
        Mat destination=new Mat(source.rows(),source.cols(),source.type());
        Imgproc.filter2D(source, destination, -1, kernel);
        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_mean_shift.JPG](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/276243/206b1baa-ca7e-2a5a-04f1-41b0ee6699bd.jpeg)