在Google Colab中获取错误(错误:(-215:断言失败)_img。函数“imwrite”中为空()

我正在使用TensorFlow进行实时目标检测。因此,第一步是收集一些标志的图像。

import cv2
import os
import time
import uuid
cv2.__version__

labels = ['hi']
number_imgs = 5

IMAGES_PATH = os.path.join('Tensorflow', 'workspace', 'images', 'collectedimages')

if not os.path.exists(IMAGES_PATH):
    if os.name == 'posix':
        !mkdir -p {IMAGES_PATH}
    if os.name == 'nt':
         !mkdir {IMAGES_PATH}
for label in labels:
    path = os.path.join(IMAGES_PATH, label)
    if not os.path.exists(path):
        !mkdir {path}

for label in labels:
    cap = cv2.VideoCapture(0)
    print('Collecting images for {}'.format(label))
    time.sleep(5)
    for imgnum in range(number_imgs):
        print('Collecting image {}'.format(imgnum))
        ret, frame = cap.read()
        imgname = os.path.join(IMAGES_PATH,label,label+'.'+'{}.jpg'.format(str(uuid.uuid1())))
        cv2.imwrite(imgname, frame)
        cv2.imshow('frame', frame)
        time.sleep(2)

        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
cap.release()
cv2.destroyAllWindows()

此代码已在Jupyter notebook上成功运行,但未在Google Colab中运行 获取此错误

Collecting images for hi Collecting image 0
--------------------------------------------------------------------------- error                                     Traceback (most recent call last) <ipython-input-23-d176419936b4> in <module>()
      7         ret, frame = cap.read()
      8         imgname = os.path.join(IMAGES_PATH,label,label+'.'+'{}.jpg'.format(str(uuid.uuid1())))
----> 9         cv2.imwrite(imgname, frame)
     10         cv2.imshow('frame', frame)
     11         time.sleep(2)

error: OpenCV(4.1.2) /io/opencv/modules/imgcodecs/src/loadsave.cpp:715: error: (-215:Assertion failed) !_img.empty() in function 'imwrite'