[java] Convert Color Image To Gray Level Image

import java.awt.color.*;
import java.awt.image.*;
import java.imageio.*;
   ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY);
   ColorConvertOp op = new ColorConvertOp(cs, null);
   try {
      BufferedImage colorImage =
          ImageIO.read(new File("C:\\MATLAB701\\work\\1100608946.jpg"));
      BufferedImage grayImage = op.filter(colorImage, null);
      JFrame grayjf = new JFrame();
      grayjf.getContentPane().add(new JButton(new ImageIcon(grayImage)));
      grayjf.setSize(colorImage.getWidth(), colorImage.getHeight());
      grayjf.setVisible(true);
   }catch(Exception e) {
      System.out.println("Error on reading color image");
   }