When using createScreenCapture from the Java robot class then the capture get's darker and darker.

First i thought it has to do with the shadows mac has around the windows so i used the program shadowkiller to get rid of them but it doesn't help.

Does anyone know where this is coming from?

1. import processing.opengl.*;
2. import java.awt.Robot;
3. import java.awt.image.BufferedImage;
4. import java.awt.Rectangle;
5. import java.awt.AWTException;
6. import java.awt.Point;
7. import java.awt.Insets;
8. 
   
9. Insets insets;
10. Robot robot;
11. 
    
12. PImage img;
13. 
    
14. Point winloc;
15. 
    
16. 
    
17. void setup() {
18.   size(screenWidth/3, screenHeight/3, OPENGL);
19. 
    
20.   try {
21.     robot = new Robot();
22.   } 
23.   catch (AWTException e) {
24.     System.out.println("Couldn't instatiate Robot class.");
25.     e.printStackTrace();
26.   }
27.   
28.   insets = frame.getInsets();
29.   
30.   smooth();
31. }
32. 
    
33. // . . . . . . . . . . . . . . . . . . .
34. 
    
35. void draw() {
36.   background(255);
37.   
38.   winloc = frame.getLocation();
39.   img = getImage(winloc.x, winloc.y + insets.top, width, height);
40.   //fastblur(img, 20);
41.   image(img, 0, 0);
42. }
43. 
    
44. // . . . . . . . . . . . . . . . . . . .
45. 
    
46. private PImage getImage(int x, int y, int w, int h) {
47.   PImage currentImage = new PImage();
48.   try {
49.     BufferedImage image = robot.createScreenCapture(
50.     new Rectangle(x, y, w, h));
51.     currentImage = new PImage(image);
52.   } 
53.   catch (NullPointerException e) {
54.     e.printStackTrace();
55.   }
56.   return currentImage;
57. }