O'Reilly logo

OpenCV with Python By Example by Prateek Joshi

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Detecting a nose

The following program shows how you detect a nose:

import cv2
import numpy as np

nose_cascade = cv2.CascadeClassifier('./cascade_files/haarcascade_mcs_nose.xml')

if nose_cascade.empty():
  raise IOError('Unable to load the nose cascade classifier xml file')

cap = cv2.VideoCapture(0)
ds_factor = 0.5

while True:
    ret, frame = cap.read()
    frame = cv2.resize(frame, None, fx=ds_factor, fy=ds_factor, interpolation=cv2.INTER_AREA)
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    nose_rects = nose_cascade.detectMultiScale(gray, 1.3, 5)
    for (x,y,w,h) in nose_rects:
        cv2.rectangle(frame, (x,y), (x+w,y+h), (0,255,0), 3)
        break

    cv2.imshow('Nose Detector', frame)

    c = cv2.waitKey(1)
    if c == 27:
        break

cap.release()
cv2.destroyAllWindows()

The output looks ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required