Java数字图像处理之图像灰度处理怎么实现

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class ImageGray extends Canvas {
    JFrame jframe = new JFrame("图像灰度处理");
    BufferedImage bufferedImage,bufferedImage_end ;
    Image image,image_end;

    public ImageGray(){
        try {
            bufferedImage = ImageIO.read(new File("D:\\EDge下载地址\\lena.jpg"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        jframe.setLayout(null);
        // 定义位置
        jframe.setBounds(200,200,800,600);
        this.setBounds(0,0,800,600);
        jframe.add(this);
        jframe.setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        image =(Image)bufferedImage;
        image_end =(Image)gray(bufferedImage);
        g.drawImage(image,0,0,null);  // 显示原图
        g.drawLine(350,10,350,600);    // 中间的线
        g.drawImage(image_end,370,0,null);  // 显示灰度图片
    }

    // 灰度处理,把原图传进去，传出来为修改后的图
    public BufferedImage gray(BufferedImage b){
        int width = b.getWidth();
        int height =b.getHeight();
        // 下面这个别忘了定义，不然会出错
        bufferedImage_end = new BufferedImage(width,height, BufferedImage.TYPE_3BYTE_BGR );
        // 双层循环更改图片的RGB值，把得到的灰度值存到bufferedImage_end中，然后返回bufferedImage_end
        for (int y = 0; y < height; y++) {
            for (int x = 0; x < width; x++) {
                // 获取到（x，y）此像素点的Colo，转化为灰度
                Color color = new Color(bufferedImage.getRGB(x,y));
                int gray = (int)(color.getRed() * 0.299 + color.getGreen() * 0.587 + color.getBlue() *0.114);
                Color color_end = new Color(gray,gray,gray);
                bufferedImage_end.setRGB(x,y,color_end.getRGB());
            }
        }
        return bufferedImage_end;
    }

    public static void main(String[] args) {
        new ImageGray();
    }
}