Image Tint does not work when exporting to PDF

Hi,

This was working fine but stopped working when I updated to the latest release. Hope somebody can help as this is a critical issue for what I do. Thanks.

import processing.pdf.*;

PImage img;

void setup() {

  size(640,360); //  when this is run, the tinted image is displayed
// size(640, 360, PDF, "test.pdf");  // however when this is run tint doesn't work anymore.

   img = loadImage("moonwalk.jpg");  

     tint(50);  
  image(img, 0, 0);  
}