the processing code:

1. 
   
2. import hypermedia.video.*;
3. import java.awt.Rectangle;
4. import processing.serial.*;        
5. 
   
6. 
   
7. int gx = 15;
8. int gy = 35;
9. int spos=90;
10. 
    
11. Serial port; 
12. 
    
13. OpenCV opencv;
14. 
    
15. // contrast/brightness values
16. int contrast_value    = 0;
17. int brightness_value  = 0;
18. 
    
19. 
    
20. 
    
21. void setup() {
22. 
    
23.     size( 320, 240 );
24. 
    
25.     opencv = new OpenCV( this );
26.     opencv.capture( width, height );                   // open video stream
27.     opencv.cascade( OpenCV.CASCADE_FRONTALFACE_ALT );  // load detection description, here-> front face detection : "haarcascade_frontalface_alt.xml"
28. 
    
29.     // print usage
30.     println( "Drag mouse on X-axis inside this sketch window to change contrast" );
31.     println( "Drag mouse on Y-axis inside this sketch window to change brightness" );
32. 
    
33.  println(Serial.list());
34.  port = new Serial(this, Serial.list()[1], 9600);
35. }
36. 
    
37. 
    
38. public void stop() {
39.     opencv.stop();
40.     super.stop();
41. }
42. 
    
43. 
    
44. 
    
45. void draw() {
46. 
    
47.     // grab a new frame
48.     // and convert to gray
49.     opencv.read();
50.     opencv.convert( RGB );
51.     opencv.contrast( contrast_value );
52.     opencv.brightness( brightness_value );
53. 
    
54.     // proceed detection
55.     Rectangle[] faces = opencv.detect( 1.2, 2, OpenCV.HAAR_DO_CANNY_PRUNING, 40, 40 );
56. 
    
57.     // display the image
58.     image( opencv.image(), 0, 0 );
59. 
    
60.     // draw face area(s)
61.     noFill();
62.     stroke(255,0,0);
63.     for( int i=0; i<faces.length; i++ ) {
64.         rect( faces[i].x, faces[i].y, faces[i].width, faces[i].height ); 
65.     }
66. }
67. 
    
68. 
    
69. 
    
70. /**
71.  * Changes contrast/brigthness values
72.  */
73. void mouseDragged() {
74.     contrast_value   = (int) map( mouseX, 0, width, -128, 128 );
75.     brightness_value = (int) map( mouseY, 0, width, -128, 128 );
76. }
77. void update(int x) 
78. {
79.   //Calculate servo postion from mouseX
80.   spos= x/4;
81. 
    
82.   //Output the servo position ( from 0 to 180)
83.   port.write(spos + "a"); 
84.     gx = x/2;
85.   gy = 100-x/2;
86. 
    
87. }
88. 
    

and the Arduino code:

1.  
2. #include <Servo.h>
3. 
   
4. Servo neck;
5. 
   
6. int xPos=0;
7. int yPos = 0;
8. 
   
9. void setup()  {
10.   Serial.begin(9600);
11.   neck.attach(13);
12. }
13. 
    
14. void loop()  {
15.   if(Serial.available() >0)  {
16.     xPos=Serial.read();
17.     yPos=Serial.read();
18.   }
19.   int xServo = map(xPos, 0, 320, 20, 70);
20.   int yServo = map(yPos, 0, 240, 20, 70);
21.   neck.write(xServo);
22. } 
23.