+- Python Forum (https://python-forum.io)
+-- Forum: Python Coding (https://python-forum.io/forum-7.html)
+--- Forum: General Coding Help (https://python-forum.io/forum-8.html)
+--- Thread: python opencv grayscale conversion error (/thread-17249.html)
python opencv grayscale conversion error - Spandora - Apr-03-2019
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'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()
RE: python opencv grayscale conversion error - heiner55 - May-26-2019
Your code runs well with the below change:
if ret == True:
nframe_gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)