Face tracking example in OpenCV

webcam-test.py

from __future__ import division
import cv, cv2, time

image_scale = 2

HAAR_CASCADE_PATH = "/usr/share/opencv/haarcascades/haarcascade_frontalface_default.xml"
def detect_faces(image):
    gray = cv.CreateImage((image.width,image.height), 8, 1)
    small_img = cv.CreateImage((cv.Round(image.width / image_scale),
                            cv.Round (image.height / image_scale)), 8, 1)
    cv.CvtColor(image, gray, cv.CV_BGR2GRAY)	
    cv.Resize(gray, small_img, cv.CV_INTER_LINEAR)
    cv.EqualizeHist(small_img, small_img)

    faces = []
    detected = cv.HaarDetectObjects(image, cascade, storage, 1.2, 2, cv.CV_HAAR_DO_CANNY_PRUNING, (100,100))
    if detected:
        for (x,y,w,h),n in detected:
            faces.append((x,y,w,h))
    return faces

cascade = cv.Load(HAAR_CASCADE_PATH)
F = []

cv.NamedWindow("w1", cv.CV_WINDOW_AUTOSIZE)
camera_index = 0
capture = cv.CaptureFromCAM(camera_index)
storage = cv.CreateMemStorage()

def repeat():
    global capture #declare as globals since we are assigning to them now
    global camera_index
    frame = cv.QueryFrame(capture)

    for (x,y,w,h) in detect_faces(frame):
        cv.Rectangle(frame, (x,y), (x+w,y+h), 255)
        print time.time(), 'target @ (%s,%s)' % (x + h/2, y + h/2)
    cv.ShowImage("w1", frame)
    c = cv.WaitKey(10)
    if(c=="n"): #in "n" key is pressed while the popup window is in focus
        camera_index += 1 #try the next camera index
        capture = cv.CaptureFromCAM(camera_index)
        if not capture: #if the next camera index didn't work, reset to 0.
            camera_index = 0
            capture = cv.CaptureFromCAM(camera_index)

while True:
    repeat()