使用imageio对PNG图像进行Java图像压缩

Question

我正在使用下面给出的代码对jpeg / png / gif图像进行图像压缩。在png图像而不是减小尺寸的情况下，图像的尺寸在增加。例如：我的图片大小为824 KB，压缩后的大小为1.2 MB。图像大小应减小或保持不变，但至少不应增大。我该如何在代码中解决此问题？

   File input = new File("digital_image_processing.png");
   BufferedImage image = ImageIO.read(input);

   File compressedImageFile = new File("compress.png");  
   OutputStream os = new FileOutputStream(compressedImageFile);

   Iterator<ImageWriter>writers = ImageIO.getImageWritersByFormatName("png");
   ImageWriter writer = (ImageWriter) writers.next();

   ImageOutputStream ios = ImageIO.createImageOutputStream(os);
   writer.setOutput(ios);

   ImageWriteParam imageWriteParam = writer.getDefaultWriteParam();

   if (imageWriteParam.canWriteCompressed()) {
      imageWriteParam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
      if (imageWriteParam.getCompressionType() == null) {
          imageWriteParam.setCompressionType(imageWriteParam.getCompressionTypes()[0]);
      }
      imageWriteParam.setCompressionQuality(imageQuality);
   }

   writer.write(null, new IIOImage(image, null, null), imageWriteParam);