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how to save detected face in opencv

asked 2015-01-30 13:46:59 -0600

sHAd0w gravatar image

in front of webcam Face detection is worked fine and when i save it as image, it save the full image but i want to save detected face only.. can u suggest me java code.

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answered 2017-03-06 01:29:55 -0600

Let assume that there is only one face. We can crop the result of the face detection and save it as follows:

import cv2
import sys

cascPath = sys.argv[1]
faceCascade = cv2.CascadeClassifier(cascPath)

video_capture = cv2.VideoCapture(0)

while True:

    # Capture frame-by-frame
    ret, frame =

    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    faces = faceCascade.detectMultiScale(
        minSize=(30, 30),

    # Draw a rectangle around the faces
    for (x, y, w, h) in faces:
        cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 0), 2)

    # Display the resulting frame
    cv2.imshow('Video', frame)

    if cv2.waitKey(1) & 0xFF == ord('q'):
    if cv2.waitKey(1) & 0xFF == ord('c'):
        crop_img = frame[y: y + h, x: x + w] # Crop from x, y, w, h -> 100, 200, 300, 400
        cv2.imwrite("face.jpg", crop_img)

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did you miss the java tag ?

berak gravatar imageberak ( 2017-03-06 01:33:27 -0600 )edit

I am sure it will be a similar idea, with a different syntax. If I get a chance I will post the java version

PatrickT gravatar imagePatrickT ( 2017-03-06 01:39:18 -0600 )edit

How to make so that rectangle was invisible when image is saved ?

RussFromSamCity gravatar imageRussFromSamCity ( 2020-06-15 13:09:15 -0600 )edit

@RussFromSamCity it's pretty obvious -- crop and save before drawing things onto the image

berak gravatar imageberak ( 2020-06-15 13:29:17 -0600 )edit

answered 2017-03-06 03:01:07 -0600

sabra gravatar image

you have x,y,w,h for each face , so just find crop function or drawrect in java syntax

rectangle(Mat img, Point pt1, Point pt2, Scalar color)
 // Draws a simple, thick, or filled up-right rectangle.
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Asked: 2015-01-30 13:46:59 -0600

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Last updated: Mar 06 '17