python opencv grayscale conversion error

[Spandora]

Hi, I am running below script. I tried with different video files format, avi/mp4 but the error is at line where each video frame is converted into grayscale. I tried this code by providing images from folder it works but when used video. There is error for grayscale conversion. Please advice.

Error:
nframe_gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.0.0) C:\projects\opencv-python\opencv\modules\imgproc\src\color.cpp:181: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

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import numpy as np import cv2   path = 'file_example_AVI_480_750kB.avi'   # below code works with OpenCV   cap = cv2.VideoCapture(path)   while(cap.isOpened()):     ret, frame = cap.read()     frameNum = frameNum+1; # to implement gray conversion of frame     nframe_gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)         #Below code, shows each frame in a moving video     #if ret == True:         # Display the resulting frame     #    cv2.imshow('Frame', frame)       if cv2.waitKey(1) & 0xFF == ord('q'):         break cap.release() cv2.destroyAllWindows()

[heiner55]

Your code runs well with the below change:

1 2	if ret == True:     nframe_gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)