diff --git a/head_posture.py b/head_posture.py
index 0d2db00..f82d20a 100644
--- a/head_posture.py
+++ b/head_posture.py
@@ -22,7 +22,10 @@
 # uncomment next line to use all points for PnP algorithm
 # points_idx = list(range(0,468)); points_idx[0:2] = points_idx[0:2:-1];
 
-frame_height, frame_width, channels = (720, 1280, 3)
+cap  = cv2.VideoCapture(0)
+_, frame = cap.read()
+frame_height, frame_width, channels = frame.shape
+del cap, frame
 
 # pseudo camera internals
 focal_length = frame_width