Python OpenCV error with CascadeClassifier

Question

import cv2
import imageio
face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('haarcascade_eye.xml')
def detect(frame):
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
for(x, y, w, h) in faces:
cv2.rectangle(frame, (x, y), (x+w, y+h), (255, 0, 0), 2)
gray_face = gray[y:y+h, x:x+w]
color_face = frame[y:y+h, x:x+w]
eyes = eye_cascade.detectMultiScale(gray_face, 1.1, 3)
for (ex, ey, ew, eh) in eyes:
cv2.rectangle(color_face, (ex, ey), (ex+ew, ey+eh), (0, 255, 0), 2)
return frame
reader = imageio.get_reader('1.mp4')
fps = reader.get_meta_data()['fps']
writer = imageio.get_writer('output.mp4', fps=fps)
for i, frame in enumerate(reader):
frame = detect(frame)
writer.append_data(frame)
print(i)
writer.close()

我收到的错误是这样的;

Traceback (most recent call last):
File "C:/Users/Mustafa Koca/PycharmProjects/mustafakoca/face_det.py", line 23, in <module>
frame = detect(frame)
File "C:/Users/Mustafa Koca/PycharmProjects/mustafakoca/face_det.py", line 9, in detect
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
cv2.error: OpenCV(4.1.2) C:projectsopencv-pythonopencvmodulesobjdetectsrccascadedetect.cpp:1689: error: (-215:Assertion failed) !empty() in function 'cv::CascadeClassifier::detectMultiScale'

Answer 1

xml文件不在当前文件夹中，而是在cv2模块的某个文件夹中，您必须使用完整路径来加载它们。

幸运的是，有带有文件夹名称的特殊变种器 -cv2.data.haarcascades

face_cascade = cv2.CascadeClassifier(cv2.data.haarcascades + 'haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier(cv2.data.haarcascades + 'haarcascade_eye.xml')

确保您可以使用os.path.join()而不是+

face_cascade = cv2.CascadeClassifier(os.path.join(cv2.data.haarcascades, 'haarcascade_frontalface_default.xml'))
eye_cascade = cv2.CascadeClassifier(os.path.join(cv2.data.haarcascades, 'haarcascade_eye.xml'))

如果加载了xml文件，那么这应该会False

print(face_cascade.empty())
print(eye_cascade.empty())