I worked it out - just had to copy the pixels into a PImage:

weird…and did you try to make offscreen detection ? I mean without displaying the camera ?

yes, I've realised when I don't display the camera image, on some frames it doesn't always copy all of the pixels for the rotated image - some times it's ok but most times it just displays a corner of the image with the rest of it black. 

ok…could you post the code ? thx

Here it is - basically I want to play/pause a video when someone is looking at the screen:

1. import android.net.Uri;
2. import android.content.Intent;
3. import android.os.Bundle;
4. import android.view.WindowManager;
5. import apwidgets.*;
6. import ketai.camera.*;
7. import ketai.cv.facedetector.*;
8. 
   
9. public String FilePath;
10. Uri Vid;
11. Intent mediaChooser;
12. APWidgetContainer widgetContainer; 
13. APButton button;
14. APVideoView videoView;
15. APWidgetContainer container;
16. KetaiCamera cam;
17. KetaiSimpleFace[] faces;
18. Integer camdelay;
19. Integer noFace =0;
20. PImage destimg;
21. Boolean VideoSet;
22. 
    
23. void onCreate(Bundle bundle) {
24.   super.onCreate(bundle);
25.   getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
26. }
27. 
    
28. void setup(){
29.   orientation(PORTRAIT);
30.   
31.   VideoSet = false;
32.   camdelay =0;
33.   
34.   destimg = createImage(240, 340, RGB);
35.   cam = new KetaiCamera(this, 320, 240, 24);
36.   cam.setCameraID(1);
37.   
38.   widgetContainer = new APWidgetContainer(this); 
39.   button = new APButton(10, 10, "Select File"); 
40.   widgetContainer.addWidget(button); 
41.   
42.   mediaChooser = new Intent(Intent.ACTION_GET_CONTENT);
43.   mediaChooser.setType("video/*");
44.   
45.   container = new APWidgetContainer(this);
46.   videoView = new APVideoView(0,0, 800, 1232, false);
47. }
48. 
    
49. void draw(){
50.    if(FilePath!=null){
51.      if(!VideoSet){
52.        println(FilePath);
53.        widgetContainer.removeWidget(button);
54.        container.addWidget(videoView);
55.        videoView.setVideoPath(FilePath); 
56.        videoView.start(); //start playing the video
57.        videoView.setLooping(true);
58.        VideoSet = true;
59.      }else{
60.         background(0); 
61.         
62.         if(camdelay>30){
63.           if (cam != null){
64.             if (!cam.isStarted()){
65.               cam.start();
66.             }
67.             image(cam, 850, 0, 320, 240);
68.             
69.             cam.loadPixels();
70.             destimg.loadPixels();
71.             for (int x = 0; x < cam.width; x++) {
72.               for (int y = 0; y < cam.height; y++ ) {
73.                   int loc = x + y*cam.width;
74.                   int destloc = destimg.pixels.length-1-(y + x*destimg.width);
75.                   destimg.pixels[destloc]  = cam.pixels[loc];
76.               }
77.             }
78.             destimg.updatePixels();
79.             
80.             faces = KetaiFaceDetector.findFaces(destimg, 20);          
81.             if(faces.length==0){
82.               videoView.pause();
83.             }else{
84.               videoView.start();
85.               println("Faces found: " + faces.length);
86.             }
87.           } 
88.         }else{
89.           camdelay+=1;
90.         }
91.      }
92.    }
93. }
94. 
    
95. void onClickWidget(APWidget widget){
96.   if(widget == button){ 
97.       startActivityForResult(mediaChooser, 1); 
98.   }
99. }
100. 
     
101. @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
102.      if(FilePath==null){
103.        Vid = data.getData();
104.        FilePath = Vid.toString();
105.      }
106. }
107. 
     
108. void onCameraPreviewEvent(){
109.   cam.read();
110. }
111. 
     
112. void onPause(){
113.   super.onPause();
114.   if (cam != null && cam.isStarted()){
115.     cam.stop();
116.   }
117. }
118.   
119. void exit(){
120.   cam.stop();
121. }