Q: how to Save only the eye image after the detection with opencv and python? How can I save only the eye image after detection with opencv and Python?
This is the code that I have tried:
import numpy as np
import cv2

face_cascade = cv2.CascadeClassifier('C:\\Users\MJ-INFO\Anaconda3\pkgs\libopencv-3.4.1-h875b8b8_3\Library\etc\haarcascades\haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('C:\\Users\MJ-INFO\Anaconda3\pkgs\libopencv-3.4.1-h875b8b8_3\Library\etc\haarcascades\haarcascade_eye.xml')

img = cv2.imread('image.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
faces = face_cascade.detectMultiScale(gray, 1.2, 5)

for (x,y,w,h) in faces:
        cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
        roi_gray = gray[y:y+h, x:x+w]
        roi_color = img[y:y+h, x:x+w]

        eyes = eye_cascade.detectMultiScale(roi_gray)

        for (ex, ey, ew, eh) in eyes:
            crop_img = roi_color[ey: ey + eh, ex: ex + ew]
            cv2.rectangle(roi_color, (ex, ey), (ex + ew, ey + eh), (0, 255, 0), 2)

cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()

But it is not working?

A: If I get your question correctly, you want to save crop_img in the loop? So, simply add cv::imwrite(...) after defining crop_img. Since you can have more than one eye, you need to think of naming your files. 
