OpenCV Face Detection with Python

#!/usr/bin/env python

# http://creatingwithcode.com/howto/face-detection-in-static-images-with-python/
# sudo apt-get install python-opencv libcv-dev opencv-doc
# face_detect.py

# Face Detection using OpenCV. Based on sample code from:
# http://python.pastebin.com/m76db1d6b

# Usage: python face_detect.py <image_file>

import sys, os
from opencv.cv import *
from opencv.highgui import *
import Image, ImageDraw

def detectObjects(image):
  """Converts an image to grayscale and prints the locations of any
    faces found"""
  grayscale = cvCreateImage(cvSize(image.width, image.height), 8, 1) # 8 is depth and 1 is channels
  cvCvtColor(image, grayscale, CV_BGR2GRAY)

  storage = cvCreateMemStorage(0)
  cvClearMemStorage(storage)
  cvEqualizeHist(grayscale, grayscale)
  cascade = cvLoadHaarClassifierCascade('/usr/share/doc/opencv-doc/examples/haarcascades/haarcascades/haarcascade_frontalface_default.xml.gz', cvSize(1,1))
  faces = cvHaarDetectObjects(grayscale, cascade, storage, 1.2, 2, CV_HAAR_DO_CANNY_PRUNING, cvSize(50,50))

  if faces.total > 0:
    for f in faces:
        print("[(%d,%d) -> (%d,%d)]" % (f.x, f.y, f.x+f.width, f.y+f.height))
        x1,y1,x2,y2=f.x,f.y,f.x+f.width,f.y+f.height
        print_rectangle(x1,y1,x2,y2) #call to a python pil

def print_rectangle(x1,y1,x2,y2): #function to modify the img
    im = Image.open(sys.argv[1])
    draw = ImageDraw.Draw(im)
    draw.rectangle([x1,y1,x2,y2])
    im.save(sys.argv[1])

def main():
  image = cvLoadImage(sys.argv[1])
  detectObjects(image)

if __name__ == "__main__":
  main()