I'm trying to change a little bit of the SimpleOpenNI example that separate user pixels from background to set pixels from an image inside the silhouette of users.

Here's my code (doesn't work, pixels are only black)

2. import SimpleOpenNI.*;
3. 
   
4. SimpleOpenNI  kinect;
5. 
   
6. boolean tracking = false;
7. int userID;
8. int[] userMap;
9. 
   
10. void setup() {
11.   size(600, 480);
12. 
    
13.   kinect = new SimpleOpenNI(this);
14.   kinect.enableDepth();
15. 
    
16.   // enable color image from the Kinect
17.   kinect.enableRGB();
18.   kinect.enableUser(SimpleOpenNI.SKEL_PROFILE_NONE);
19. 
    
20.   // turn on depth-color alignment
21.   kinect.alternativeViewPointDepthToImage();
22. 
    
23.   // load the background image
24.   backgroundImage = loadImage("lua.jpg");
25. }
26. 
    
27. void draw() {
28. 
    
29.   // display the background image
30.   background(0);
31.   kinect.update();
32.   if (tracking) {
33. 
    
34.     // get the Kinect color image
35.   PImage rgbImage = loadImage("empire_state.jpg");
36.     // prepare the color pixels
37.     rgbImage.loadPixels();
38.     loadPixels();
39. 
    
40.     userMap = kinect.getUsersPixels(SimpleOpenNI.USERS_ALL);
41.     for (int i =0; i < userMap.length; i++) {
42.       for (int j = 0; j < rgbImage.pixels.length; j++) {
43.         color c = rgbImage.pixels[j];
44.         float r = red(c);
45.         float g = green(c);
46.         float b = blue(c);
47.       // if the pixel is part of the user
48.       if (userMap[i] != 0) {
49.         // set the sketch pixel to the color pixel
50.         pixels[i] = color((r + g + b) / 3);
51.       }
52.      }      
53.     }    
54.     rgbImage.updatePixels();
55.     updatePixels();
56.   }
57. }
58. 
    
59. void onNewUser(int uID) {
60.   userID = uID;
61.   tracking = true;
62.   println("tracking");
63. }
 

Any ideas?