faster detection and timing in facedetect.py

samples/python2/facedetect.py

 import numpy as np
 import cv2, cv
 from video import create_capture
+from common import clock, draw_str
 
 help_message = '''
 USAGE: facedetect.py [--cascade <cascade_fn>] [--nested-cascade <cascade_fn>] [<video_source>]
 '''
 
 def detect(img, cascade):
-    rects = cascade.detectMultiScale(img, scaleFactor=1.3, minNeighbors=4, minSize=(30, 30))
+    rects = cascade.detectMultiScale(img, scaleFactor=1.3, minNeighbors=4, minSize=(30, 30), flags = cv.CV_HAAR_SCALE_IMAGE)
     if len(rects) == 0:
         return []
     rects[:,2:] += rects[:,:2]
@@ -37,6 +38,8 @@ if __name__ == '__main__':
         ret, img = cam.read()
         gray = cv2.cvtColor(img, cv.CV_BGR2GRAY)
         gray = cv2.equalizeHist(gray)
+        
+        t = clock()
         rects = detect(gray, cascade)
         vis = img.copy()
         draw_rects(vis, rects, (0, 255, 0))
@@ -45,7 +48,9 @@ if __name__ == '__main__':
             vis_roi = vis[y1:y2, x1:x2]
             subrects = detect(roi.copy(), nested)
             draw_rects(vis_roi, subrects, (255, 0, 0))
+        dt = clock() - t
 
+        draw_str(vis, (20, 20), 'time: %.1f ms' % (dt*1000))
         cv2.imshow('facedetect', vis)
 
         if cv2.waitKey(5) == 27: