corner points not found when executing the calibration.py

[USTBVEO]

cv2.error: OpenCV(4.6.0) D:\a\opencv-python\opencv-python\opencv\modules\calib3d\src\calibration.cpp:3694: error: (-215:Assertion failed) nimages > 0 in function 'cv::calibrateCameraRO'

I cannot find the corner points in the given pictures in file calibration/calibration.py.

[zlj-zz]

I think it may be that your environment is too dark, and it needs some contrast.

[USTBVEO]

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