import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class ConvertImageFile {
  public static void main(String[] args) {
    BufferedImage bufferedImage;
    try {
      // read image file
      bufferedImage = ImageIO.read(new File("c:\\java.png"));
      // create a blank, RGB, same width and height, and a white
      // background
      BufferedImage newBufferedImage = new BufferedImage(
          bufferedImage.getWidth(), bufferedImage.getHeight(),
          BufferedImage.TYPE_INT_RGB);
      // TYPE_INT_RGB:創(chuàng)建一個RBG圖像，24位深度，成功將32位圖轉化成24位
      newBufferedImage.createGraphics().drawImage(bufferedImage, 0, 0,
          Color.WHITE, null);
      // write to jpeg file
      ImageIO.write(newBufferedImage, "jpg", new File("c:\\java.jpg"));
      System.out.println("Done");
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}