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

Question

这是我第一次尝试在OpenCV 3.1中检测面孔和眼睛。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()

我得到了一个错误：

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

有人能告诉我我的错误在哪里吗？我也试过：

gray = cv.cvtColor(img, cv.COLOR_BAYER_GR2GRAY)如PyCharm所建议的。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错误:断言失败(！空())在cv：：Cascade分类器：：检测多尺度

告诉您分类器是空的，因为您没有正确加载xml文件。

使用xml文件的完整路径确保正确加载它们。

Answer 2

D:\Build\OpenCV\opencv-3.1.0\modules\imgproc\src\demosaicing.cpp，错误:断言失败(scn == 1& dcn == 1)在cv::demosaicing中，文件OpenCV行1630回溯(最近一次调用)：文件"C:/Users/hedon/PycharmProjects/deneme_1.1/ilk.py"，第11行，在===cv.cvtColor中错误: D:\Build\OpenCV\opencv-3.1.0\modules\imgproc\src\demosaicing.cpp:1630:错误:函数cv：：== 1中的(-215) scn == 1 && dcn ==1

这一问题来自：

cv2.imread

您应该检查图像是否存在于您给定的路径中，如果它有有效的编号，则检查count变量。