如何在 pycharm 中修复此错误？ cv2.error: OpenCV(3.4.2) 错误: (-215:Assertion failed)

Question

I'm new to python and opencv, I want to crop face images from my input images. I really don't know where went wrong, could anyone help me to fix it?

I think there might be something wrong with the directory of input images. So I have changed all the '/' to '\\', it's still not right. Also, under this directory, there are many subfolders, and in each subfolder, there are some raw images.

import cv2
import os


def fetch_face_pic(img,face_cascade):
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    faces = face_cascade.detectMultiScale(gray, scaleFactor=1.1, minNeighbors=10, minSize = (30, 30), flags = 0)

    for(x, y, w, h) in faces:
        crop = img[y:y+h, x:x+w]
    return crop


face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_defalut.xml')

#path_save = '/Users/oysdfx/Desktop/Face-anti-spoofing-master/crop/ImposterCrop'
path_read = '/Users/oysdfx/Desktop/Face-anti-spoofing-master/raw/ImposterRaw'

for file in os.listdir(path_read):
    pic = os.path.join(path_read, file)
    img = cv2.imread(pic)
    crop = fetch_face_pic(img, face_cascade)

    resized_img = cv2.resize(img, (64, 64), interpolation=cv2.INTER_CUBIC)
    cv2.imwrite(pic, resized_img)

Actually I want to crop out faces from input images, and save them in a new folder. I don't know how to implement this. I run this piece of code and get error as follows:

Traceback (most recent call last):
  File "/Users/oysdfx/Desktop/Undergraduate_Thesis/Face_Anti-Spoofing/crop_face.py", line 86, in <module>
    crop = fetch_face_pic(img, face_cascade)
  File "/Users/oysdfx/Desktop/Undergraduate_Thesis/Face_Anti-Spoofing/crop_face.py", line 70, in fetch_face_pic
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(3.4.2) /opt/concourse/worker/volumes/live/9523d527-1b9e-48e0-7ed0-a36adde286f0/volume/opencv-suite_1535558719691/work/modules/imgproc/src/color.hpp:253: error: (-215:Assertion failed) VScn::contains(scn) && VDcn::contains(dcn) && VDepth::contains(depth) in function 'CvtHelper'


Process finished with exit code 1

Answer 1

This has nothing to do with your IDE, PyCharm. Your image path is probably wrong. Check if img is None before moving forward. If so, print the path ( pic ) and you will see it is wrong.

# [...]

for file in os.listdir(path_read):
    pic = os.path.join(path_read, file)
    img = cv2.imread(pic)
    if img is None:
        raise Exception('Invalid image: {}'.format(pic))
    crop = fetch_face_pic(img, face_cascade)

# [...]