public static void main(String[] args) {

  //文件与BufferedImage间的转换
  BufferedImage bi=file2img("test.jpg"); //读取图片
  BufferedImage bii=img_color_contrast(bi,100);
  img2file(bii,"jpg","test1.jpg"); //生成图片

 }

//图片对比度调整
 public static BufferedImage img_color_contrast(BufferedImage imgsrc, int contrast) {
  try {
   int contrast_average = 128;
   //创建一个不带透明度的图片
   BufferedImage back=new BufferedImage(imgsrc.getWidth(), imgsrc.getHeight(),BufferedImage.TYPE_INT_RGB);
   int width = imgsrc.getWidth(); 
   int height = imgsrc.getHeight(); 
   int pix;
   for (int i = 0; i < height; i++) { 
    for (int j = 0; j < width; j++) { 
     int pixel = imgsrc.getRGB(j, i); 
     Color color = new Color(pixel);

     if (color.getRed() < contrast_average)
     {
      pix = color.getRed()- Math.abs(contrast);
      if (pix < 0) pix = 0;
     }
     else
     {
      pix = color.getRed() + Math.abs(contrast);
      if (pix > 255) pix = 255;
     }
     int red= pix;
     if (color.getGreen() < contrast_average)
     {
      pix = color.getGreen()- Math.abs(contrast);
      if (pix < 0) pix = 0;
     }
     else
     {
      pix = color.getGreen() + Math.abs(contrast);
      if (pix > 255) pix = 255;
     }
     int green= pix; 
     if (color.getBlue() < contrast_average)
     {
      pix = color.getBlue()- Math.abs(contrast);
      if (pix < 0) pix = 0;
     }
     else
     {
      pix = color.getBlue() + Math.abs(contrast);
      if (pix > 255) pix = 255;
     }
     int blue= pix; 

     color = new Color(red,green,blue);
     int x=color.getRGB();
     back.setRGB(j,i,x);
    }
   }
   return back;
  } catch (Exception e) {
   e.printStackTrace();
   return null;
  }
 }

//读取图片
 public static BufferedImage file2img(String imgpath) {
  try {
   BufferedImage bufferedImage=ImageIO.read(new File(imgpath));
   return bufferedImage;
  } catch (Exception e) {
   e.printStackTrace();
   return null;
  }
 }
 //保存图片,extent为格式，"jpg"、"png"等
 public static void img2file(BufferedImage img,String extent,String newfile) {
  try {
   ImageIO.write(img, extent, new File(newfile));
  } catch (Exception e) {
   e.printStackTrace();
  }
 }