Python opencv face detection example

facedetect-example.py

#!/usr/bin/env /usr/local/bin/python


import glob, os, sys, uuid
import cv
from Foundation import *
from objc import *
from AppKit import *
from PIL import *


class FaceDetect():
    def __init__(self):
        NSApplication.sharedApplication().activateIgnoringOtherApps_(True)
        
        cv.NamedWindow ("FaceDetect", 1)
        
        self.capture = cv.CaptureFromCAM( 0 )
        self.writer = None

    def detect(self):
        faces = []
        
        cv.CvtColor(self.frame, self.grayscale, cv.CV_RGB2GRAY)

        #equalize histogram
        cv.EqualizeHist(self.grayscale, self.grayscale)
        
        # detect objects
        
        for cascade in self.cascades:
            faces.extend( 
                cv.HaarDetectObjects(
                    image=self.frame, 
                    cascade=cascade, 
                    storage=self.storage, 
                    scale_factor=1.2,
                    min_neighbors=2, 
                    flags=cv.CV_HAAR_DO_CANNY_PRUNING)
            )        
            for (x,y,w,h),n in faces:
                if n > 10:
                     cv.Circle(self.frame, (int(2*x+w)/2,int(2*y+h)/2), int(w+h+h*0.5)/4, (128, 255, 128))
                cv.Rectangle(self.frame, (x,y), (x+w,y+h), 255)    
    def procKey(self, k):
        if k == 0x1b: # ESC
            print 'ESC pressed. Exiting ...'
            sys.exit(1)
            return False
        
        elif  k == ord('s'):
            currentFrame = cv.GetCaptureProperty(self.capture, cv.CV_CAP_PROP_POS_MSEC )
            cv.SetCaptureProperty(self.capture, cv.CV_CAP_PROP_POS_MSEC , abs(currentFrame+1000) )
        
        elif  k == ord('b'):
            currentFrame = cv.GetCaptureProperty(self.capture, cv.CV_CAP_PROP_POS_MSEC )
            cv.SetCaptureProperty(self.capture, cv.CV_CAP_PROP_POS_MSEC , abs(currentFrame-1000) )  
        
        elif  k == ord('o'):
            op = NSOpenPanel.openPanel()
            op.runModalForTypes_(None)
                
            if len(op.filenames()):
                self.capture = cv.CreateFileCapture(op.filenames()[0])
                self.writer = cv.CreateVideoWriter(
                    str(uuid.uuid1())+".avi",
                    cv.CV_FOURCC('D','I','V','X'), 
                    cv.GetCaptureProperty(self.capture, cv.CV_CAP_PROP_FPS),
                    (int(cv.GetCaptureProperty(self.capture, cv.CV_CAP_PROP_FRAME_WIDTH)),  int(cv.GetCaptureProperty(self.capture, cv.CV_CAP_PROP_FRAME_HEIGHT))), 
                    True)
                    
            op.setReleasedWhenClosed_(True)
            op.close()
          
        elif  k >= ord('0') and  k <= ord('9'):
            self.capture = cv.CaptureFromCAM( k-48 )
            self.writer = None

    def run(self):
        # check if capture device is OK
        if not self.capture:
            print "Error opening capture device"
            sys.exit(1)
        
        if self.capture:
            self.frame = cv.QueryFrame(self.capture)
        
        if self.frame:
            self.image_size = cv.GetSize(self.frame)
        
        if self.writer:
            cv.WriteFrame(self.writer, self.frame)
        
        


        # create grayscale version
        self.grayscale = cv.CreateImage(self.image_size, 8, 1)

        # create storage
        self.storage = cv.CreateMemStorage(1024)
        self.cascades  = []
        self.cascades.append(cv.Load('haarcascade_frontalface_alt2.xml'))        

        while 1:
            # do forever
            if self.capture:
                self.frame = cv.QueryFrame(self.capture)
            if self.frame:
                self.image_size = cv.GetSize(self.frame)
            if self.image_size:
                self.grayscale = cv.CreateImage(self.image_size, 8, 1)
            
            if self.frame is None:
                break
                       
            # face detection
            self.detect()
            
            if self.writer:
                cv.WriteFrame(self.writer, self.frame)
            

            # display webcam image
            if self.frame:
                cv.ShowImage('FaceDetect', self.frame)
            
            
            # handle events
            k = cv.WaitKey(10)
            
            if  self.procKey(k) == False:
                break

if __name__ == "__main__":
    print "Press ESC to exit ..."
    face_detect = FaceDetect()
    face_detect.run() 

howto.md

do this

easy_install pyobjc==2.2 brew install pil brew install opencv

then

python facedetect-example.py

have fun