title: How to make a color transparent in a BufferedImage and save as PNG
body: <p>I have been searching the web for this, but I havent found any decent help.</p>
  
  <p>I have a BufferedImage, which I have read in with ImageIO. Now I would like to make a certain color in that image to transparent, and save the image as PNG.</p>
  
  <p>I know I cannot just "paint" the transparent color for obvious reasons, so I am guessing I need some kind of a filter.</p>
  
  <p>Anyone got some sample code for this?</p>