python - cv.cvtColor(img, cv.COLOR_BGR2GRAY) 不起作用

Question

这是我第一次尝试在 OpenCV 3.1 中检测面部和眼睛。这是我的代码:

import cv2 as cv
import numpy as np

face_cascade = cv.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_cascade = cv.CascadeClassifier('haarcascade_eye.xml')

cam = cv.VideoCapture(0)

while True:
    tf, img = cam.read()
    gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)

    faces = face_cascade.detectMultiScale(gray, 1.3, 5)

    for (x, y, w, h) in faces:
        img = cv.rectangle(img, (x, y), (x + w, y + h), (255, 0, 0), 2)

        roi_gray = gray[y:y + h, x:x + w]
        roi_color = img[y:y + h, x:x + w]
        eyes = eye_cascade.detectMultiScalenter code heree(roi_gray)

        for (ex, ey, ew, eh) in eyes:
            cv.rectangle(roi_color, (ex, ey), (ex + ew, ey + eh), (0, 255, 0), 2)

        print(tf)
        cv.imshow('my cam', img)
        key = cv.waitKey(1)
        if key  == 27:
            break
cam.release()
cv.destroyAllWindows()

我得到了这个错误:

OpenCV Error: Assertion failed (!empty()) in cv::CascadeClassifier::detectMultiScale, file D:\Build\OpenCV\opencv-3.1.0\modules\objdetect\src\cascadedetect.cpp, line 1639
Traceback (most recent call last):
  File "C:/Users/hedon/PycharmProjects/deneme_1.1/ilk.py", line 13, in <module>
    faces = face_cascade.detectMultiScale(gray, 1.3, 5)
cv2.error: D:\Build\OpenCV\opencv-3.1.0\modules\objdetect\src\cascadedetect.cpp:1639: error: (-215) !empty() in function cv::CascadeClassifier::detectMultiScale

谁能告诉我哪里错了？我也试过:

gray = cv.cvtColor(img, cv.COLOR_BAYER_GR2GRAY) 正如 PyCharm 建议的那样。同样的错误:

OpenCV Error: Assertion failed (scn == 1 && dcn == 1) in cv::demosaicing, file D:\Build\OpenCV\opencv-3.1.0\modules\imgproc\src\demosaicing.cpp, line 1630
Traceback (most recent call last):
  File "C:/Users/hedon/PycharmProjects/deneme_1.1/ilk.py", line 11, in <module>
    gray = cv.cvtColor(img, cv.COLOR_BAYER_BG2GRAY)
cv2.error: D:\Build\OpenCV\opencv-3.1.0\modules\imgproc\src\demosaicing.cpp:1630: error: (-215) scn == 1 && dcn == 1 in function cv::demosaicing

Answer 1

OpenCV Error: Assertion failed (!empty()) in cv::CascadeClassifier::detectMultiScale

告诉您分类器为空，因为您没有正确加载 xml 文件。

使用 xml 文件的完整路径以确保正确加载它们。