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python - 我正在尝试使用 OpenCV 的项目，但无法克服此错误

问题描述

cv2.error: OpenCV(4.4.0) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-2y91i_7w\opencv\modules\objdetect\src\cascadedetect.cpp:1689: error: (-215:Assertion failed) !empty() in function 'cv::CascadeClassifier::detectMultiScale'

[ WARN:0] global C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-2y91i_7w\opencv\modules\videoio\src\cap_msmf.cpp (435) `anonymous-namespace'::SourceReaderCB::~SourceReaderCB terminating async callback

这是我面临的错误

下面是我的代码

import cv2
face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
smile_cascade = cv2.CascadeClassifier('haarcascade_smile.xml')

def detect(gray,frame):
    faces = face_cascade.detectMultiScale(gray, 1.3, 5)
    for (x,y,w,h) in faces:
        cv2.rectangle(frame, (x,y), ((x+w),(y+h)), (2555,0,0), 2)
        roi_gray = gray[y:y + h, x:x + w]
        roi_color = frame[y:y + h, x:x +w]
        smiles = smile_cascade.detectMultiScale(roi_gray, 1.8,20)

        for (sx,sy,sw,sh) in smiles:
            cv2.rectangle(roi_color ,(sx,sy), ((sx + sw) , (sy + sh)),(0,0,225),2)
        return frame
video_capture = cv2.VideoCapture(0)
while True:
    _, frame = video_capture.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    canvas = detect(gray, frame)

    cv2.imshow('Video', canvas)

    if cv2.waitkey(1) & xff == qrd('q'):
        break
video_capture.release()
cv2.destroyAllWindows()

标签： pythonopencv

解决方案

我得到了一个不同的错误并修复了方法return行的缩进detect()，请参阅注释。

此外，函数存在一些错误waytkey()，实际上是waitKey().

这应该有效（至少它在我的机器上有效）：

import cv2
face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
smile_cascade = cv2.CascadeClassifier('haarcascade_smile.xml')

def detect(gray, frame):
    faces = face_cascade.detectMultiScale(gray, 1.3, 5)
    for (x,y,w,h) in faces:
        cv2.rectangle(frame, (x,y), ((x+w),(y+h)), (2555,0,0), 2)
        roi_gray = gray[y:y + h, x:x + w]
        roi_color = frame[y:y + h, x:x +w]
        smiles = smile_cascade.detectMultiScale(roi_gray, 1.8,20)

        for (sx,sy,sw,sh) in smiles:
            cv2.rectangle(roi_color ,(sx,sy), ((sx + sw) , (sy + sh)),(0,0,225),2)
    return frame # << outdent

video_capture = cv2.VideoCapture(0)
while True:
    ret, frame = video_capture.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    canvas = detect(gray, frame)
    cv2.imshow('Video', canvas)

    # changed here below the waitKey() and added ret:
    keypressed = cv2.waitKey(10)
    if keypressed == ord('q') or not ret:
        break

video_capture.release()
cv2.destroyAllWindows()

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