title: Save buffered image with transparent background
body: <p>I'm saving the image of a signature as a .jpg picture. I use graphic2d to paint on the image every pixel of the signature (gotten with a signature tablet) and it works perfectly but I'm always gettin a white background.
  If I want to put the signature on a PDF document, the borders of the white square of the jpg image covers some of the words of the PDF.</p>
  
  <p>What I want to get is to save the jpg image with a transparent background, so when I put it on the PDF there are no words covered with the white image background but just the signature lines.</p>
  
  <p>This is the code that saves the buffered image. It does it with the white background. </p>
  
  <pre><code> // This method refers to the signature image to save
  private RenderedImage getImage() {
  
      int width = tabletWidth;
      int height = tabletHeight;
  
      // Create a buffered image in which to draw
      BufferedImage bufferedImage = new BufferedImage(width, height,
              BufferedImage.TYPE_INT_RGB);
  
      // Create a graphics contents on the buffered image
      Graphics2D g2d = bufferedImage.createGraphics();
  
      // Draw graphics
      g2d.setColor(Color.WHITE);
      g2d.fillRect(0, 0, width, height);
  
      drawPoints(Tablet.getPenPoints(), g2d, Color.BLACK);
  
      // Graphics context no longer needed so dispose it
      g2d.dispose();
  
      return bufferedImage;
  }
  </code></pre>
  
  <p>I tried to set it transparent but with no success, so I posted this working part.</p>