title: Image size increased twice when convert from JPG to PNG using thumbnailator
body: <p>Am using Thumbnailator to compress the image in my application. Everything is work fine alone when i try to convert the JPG image to PNG. At this process the size of an image getting twice after compressing. Following code is am used to convert image.</p>
  
  <pre><code>File a=new File("C:\\Users\\muthu\\Downloads\\SampleJPGImage_5mbmb.jpg");
  Thumbnails.of(a).scale(1).outputQuality(0.5).toFile("C:\\Users\\muthu\\Downloads\\SampleJPGImage_5mbmb1.png");
  </code></pre>
  
  <p>using pure java also doing same and code is follows</p>
  
  <pre><code>BufferedImage bufferedImage = ImageIO.read(new File("C:\\Users\\muthu\\Downloads\\SampleJPGImage_5mbmb.jpg"));
  ImageIO.write(bufferedImage, "png", new File("C:\\Users\\muthu\\Downloads\\javaPngimage.png"));
  </code></pre>
  
  <p>Ex: 5MB image file is converted to 32MB file. I should not go for resize to compress. Am stuck with this</p>