added lk_track.py sample (currently as a comparison between flow tracker implementations)

samples/python2/facedetect.py

@@ -15,7 +15,7 @@ def detect(img, cascade):
 
 def draw_rects(img, rects, color):
     for x1, y1, x2, y2 in rects:
-        cv2.rectangle(img, (x1, y1), (x2, y2), color)
+        cv2.rectangle(img, (x1, y1), (x2, y2), color, 2)
 
 if __name__ == '__main__':
     import sys, getopt
@@ -38,7 +38,7 @@ if __name__ == '__main__':
         gray = cv2.cvtColor(img, cv.CV_BGR2GRAY)
         gray = cv2.equalizeHist(gray)
         rects = detect(gray, cascade)
-        vis = cv2.cvtColor(gray, cv.CV_GRAY2BGR)
+        vis = img.copy()
         draw_rects(vis, rects, (0, 255, 0))
         for x1, y1, x2, y2 in rects:
             roi = gray[y1:y2, x1:x2]

samples/python2/lk_track.py

@@ -0,0 +1,87 @@
+import numpy as np
+import cv2, cv
+import video
+from common import anorm2, draw_str
+from time import clock
+
+help_message = '''
+USAGE: lk_track.py [<video_source>]
+
+Keys:
+  1 - toggle old/new CalcOpticalFlowPyrLK implementation
+  SPACE - reset features
+'''
+
+
+
+
+lk_params = dict( winSize  = (3, 3), 
+                  maxLevel = 2, 
+                  criteria = (cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, 10, 0.03),
+                  derivLambda = 0.0 )    
+
+feature_params = dict( maxCorners = 500, 
+                       qualityLevel = 0.1,
+                       minDistance = 5,
+                       blockSize = 5 )
+
+def calc_flow_old(img0, img1, p0):
+    p0 = [(x, y) for x, y in p0.reshape(-1, 2)]
+    h, w = img0.shape[:2]
+    img0_cv = cv.CreateMat(h, w, cv.CV_8U)
+    img1_cv = cv.CreateMat(h, w, cv.CV_8U)
+    np.asarray(img0_cv)[:] = img0
+    np.asarray(img1_cv)[:] = img1
+    t = clock()
+    features, status, error  = cv.CalcOpticalFlowPyrLK(img0_cv, img1_cv, None, None, p0, 
+        lk_params['winSize'], lk_params['maxLevel'], (cv.CV_TERMCRIT_EPS | cv.CV_TERMCRIT_ITER, 10, 0.03), 0, p0)
+    return np.float32(features), status, error, clock()-t
+
+def main():
+    import sys
+    try: video_src = sys.argv[1]
+    except: video_src = video.presets['chess']
+
+    track_len = 4
+    tracks = []
+    cam = video.create_capture(video_src)
+    old_mode = True
+    while True:
+        ret, frame = cam.read()
+        vis = frame.copy()
+        if len(tracks) > 0:
+            p0 = np.float32([tr[-1] for tr in tracks]).reshape(-1, 1, 2)
+            img0 = cv2.cvtColor(prev_frame, cv.CV_BGR2GRAY)
+            img1 = cv2.cvtColor(frame, cv.CV_BGR2GRAY)
+            if old_mode:
+                p1,  st, err, dt = calc_flow_old(img0, img1, p0)
+            else:
+                t = clock()
+                p1,  st, err = cv2.calcOpticalFlowPyrLK(img0, img1, p0, **lk_params)
+                dt = clock()-t
+            for tr, (x, y) in zip(tracks, p1.reshape(-1, 2)):
+                tr.append((x, y))
+                if len(tr) > 10:
+                    del tr[0]
+                cv2.circle(vis, (x, y), 2, (0, 255, 0), -2)
+            cv2.polylines(vis, [np.int32(tr) for tr in tracks], False, (0, 255, 0))
+            draw_str(vis, (20, 20), ['new', 'old'][old_mode]+' mode')
+            draw_str(vis, (20, 40), 'time: %.02f ms' % (dt*1000))
+        prev_frame = frame.copy()
+
+        cv2.imshow('img', vis)
+        ch = cv2.waitKey(5)
+        if ch == 27:
+            break
+        if ch == ord(' ') or len(tracks) == 0:
+            gray = cv2.cvtColor(frame, cv.CV_BGR2GRAY)
+            p = cv2.goodFeaturesToTrack(gray, **feature_params)
+            p = [] if p is None else p.reshape(-1, 2)
+            tracks = []
+            for x, y in np.float32(p):
+                tracks.append([(x, y)])
+        if ch == ord('1'):
+            old_mode = not old_mode
+
+if __name__ == '__main__':
+    main()