我为什么会遇到_cv2出现src.empty()错误

Question

我不断遇到错误：

[ WARN:0] global C:UsersappveyorAppDataLocalTemp1pip-req-build-wvn_it83opencvmodulesvideoiosrccap_msmf.cpp (434) `anonymous-namespace'::SourceReaderCB::~SourceReaderCB terminating async callback
Traceback (most recent call last):
File "C:UsersHomePycharmProjectshandtrackingHandTrackingModule.py", line 60, in <module>
main()
File "C:UsersHomePycharmProjectshandtrackingHandTrackingModule.py", line 47, in main
img = detector.findHands(img)
File "C:UsersHomePycharmProjectshandtrackingHandTrackingModule.py", line 19, in findHands
imgRGB = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.5.1) C:UsersappveyorAppDataLocalTemp1pip-req-build-wvn_it83opencvmodulesimgprocsrccolor.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

每当我尝试运行下面的代码时，我不知道为什么。有人能帮我吗？

import cv2
import mediapipe as mp
import time

class handDetector():
def __init__(self, mode=False, maxHands=2, detectionCon=0.5, trackCon=0.5):
self.mode = mode
self.maxHands = maxHands
self.detectionCon = detectionCon
self.trackCon = trackCon
self.mpHands = mp.solutions.hands
self.hands = self.mpHands.Hands(self.mode, self.maxHands, self.detectionCon, self.trackCon)  
self.mpDraw = mp.solutions.drawing_utils

def findHands(self, img, draw=True):
imgRGB = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
results = self.hands.process(imgRGB) 

if results.multi_hand_landmarks:
for handLms in results.multi_hand_landmarks:
if draw:
self.mpDraw.draw_landmarks(img, handLms, self.mpHands.HAND_CONNECTIONS)
return img

def main():
pTime = 0
cTime = 0
cap = cv2.VideoCapture(1)
detector = handDetector()
while True:
success, img = cap.read()
img = detector.findHands(img)
cTime = time.time()
fps = 1 / (cTime - pTime)
pTime = cTime
cv2.putText(img, str(int(fps)), (10, 70), cv2.FONT_HERSHEY_SCRIPT_SIMPLEX, 1, (255, 0, 255), 3)
cv2.imshow("Image", img)
cv2.waitKey(1)

if __name__ == "__main__":
main()

Answer 1

表示从success, img = cap.read()返回的img为None，也表示返回的success为False。

如果你的电脑内置了网络摄像头，那么你可以尝试cap = cv2.VideoCapture(0)。如果没有，你可以尝试将视频文件的路径传递到括号中，比如

cap = cv2.VideoCapture("C:/Users/Username/Desktop/video.mp4")

最后，如果你试图访问的是外部网络摄像头/摄像头，你可以看看如何使用OpenCV访问外部网络摄像头？。

Answer 2

如果你的电脑内置了网络摄像头，那么你可以尝试cap=cv2.视频捕获(0(。如果没有，您可以尝试将0替换为1cap=cv.VideoCapture(1(