利用java怎么实现一个将图片去色的功能

package com.epoint.wdg.test;  import java.awt.Color; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException;  import javax.imageio.ImageIO;  public class ImgTest {   public static void main(String[] args) throws IOException {     File file=new File("C://Users/wdg/Desktop/people.png");     //showParamterofImg(file);     File file2=changeImgtoGray(file);     grayPicToBW(file2);   }   public static void getRGB(File file) throws IOException{     int []rgb =new int[3];     BufferedImage img=ImageIO.read(file);     int pixel=img.getRGB(2, 3);     // 下面三行代码将一个数字转换为RGB数字      rgb[0] = (pixel & 0xff0000) >> 16;      rgb[1] = (pixel & 0xff00) >> 8;      rgb[2] = (pixel & 0xff);      System.out.println(rgb[0]+"-"+rgb[1]+"-"+rgb[2]);        }   //把图片变灰色   public static File changeImgtoGray(File file) throws IOException{     float []rgb =new float[3];     BufferedImage img=ImageIO.read(file);     //现在我需要获取到没一点的rgb     int y=img.getHeight();     int x=img.getWidth();     BufferedImage grayImage = new BufferedImage(x, y, BufferedImage.TYPE_BYTE_GRAY);     for(int i=0;i<x;i++){       for(int j=0;j<y;j++){         int pixel=img.getRGB(i, j);       // grayImage.setRGB(startX, startY, w, h, rgbArray, offset, scansize);          rgb[0] = (pixel & 0xff0000) >> 16;           rgb[1] = (pixel & 0xff00) >> 8;           rgb[2] = (pixel & 0xff);          int gray=(int) (rgb[0] * 0.3 + rgb[1] * 0.59 + rgb[2] * 0.11);          Color color=new Color(gray,gray,gray);          img.setRGB(i, j, color.getRGB());        }     }     File newFile = new File("C://Users/wdg/Desktop/"+"/method5.jpg");      ImageIO.write(img, "jpg", newFile);      // grayPicToBW(newFile);     return newFile;   }