cvtColor函数中出现openCV错误:断言失败(scn == 3 || scn == 4)
cvtColor函数中出现openCV错误:断言失败(scn == 3 || scn == 4)
提问于 2014-12-02 19:17:02
我想简单地加载一个视频文件，将其转换为灰度，并显示它。下面是我的代码：
import numpy as np
import cv2
cap = cv2.VideoCapture('cars.mp4')
while(cap.isOpened()):
# Capture frame-by-frame
ret, frame = cap.read()
#print frame.shape
# Our operations on the frame come here
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# Display the resulting frame
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()这个视频一直播放到最后。然后它冻结，窗口变得没有响应，我在终端中得到以下错误：
OpenCV Error: Assertion failed (scn == 3 || scn == 4) in cvtColor, file /home/clive/Downloads/OpenCV/opencv-2.4.9/modules/imgproc/src/color.cpp, line 3737
Traceback (most recent call last):
File "cap.py", line 13, in <module>
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.error: /home/clive/Downloads/OpenCV/opencv-2.4.9/modules/imgproc/src/color.cpp:3737: error: (-215) scn == 3 || scn == 4 in function cvtColor我取消了对语句print frame.shape的注释。它一直在打印720,1028,3。但在视频播放到结束后，它会冻结，一段时间后它会关闭并返回
print frame.shape
AttributeError: 'NoneType' object has no attribute 'shape'我知道这个断言失败消息通常意味着我正在尝试转换一个空图像。在开始使用if(ret)：语句处理图像之前，我添加了对空图像的检查。(有没有其他方法？？)
import numpy as np
import cv2
cap = cv2.VideoCapture('cars.mp4')
while(cap.isOpened()):
# Capture frame-by-frame
ret, frame = cap.read()
#print frame.shape
if(ret): #if cam read is successfull
# Our operations on the frame come here
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# Display the resulting frame
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()这一次，视频一直播放到最后，窗口仍然冻结并在几秒钟后关闭。这一次，我没有得到任何错误。但是为什么窗口会冻结呢？我怎么才能修复它呢？
回答 1
Stack Overflow用户
发布于 2014-12-02 19:40:57
waitKey()部分不应依赖于帧的有效性，请将其移出条件：
import numpy as np
import cv2
cap = cv2.VideoCapture('cars.mp4')
while(cap.isOpened()):
# Capture frame-by-frame
ret, frame = cap.read()
#print frame.shape
if(ret): #if cam read is successfull
# Our operations on the frame come here
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
# Display the resulting frame
cv2.imshow('frame',gray)
else:
break
# this should be called always, frame or not.
if cv2.waitKey(1) & 0xFF == ord('q'):
break页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/27248068
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