error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'

用Python打开图像始终提示错误

error: OpenCV(4.1.1) C:\projects\opencv-python\opencv\modules\highgui\src\window.cpp:352:
error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'

1 import cv2 as cv
2 img = cv.imread('D:\BjutDeeplearning\Opencvtest\python-opencv05\\black.jpg')
3 cv.imshow("img", img)
4 print(img.shape)
5 cv.waitKey(0)
6 cv.destroyAllWindows()

三个注意：

图片放在非中文路径进行读取，

图片改为非中文名，

图片名称前用双\\或者路径前面加r，使用原始字符串：

r'D:\BjutDeeplearning\Opencvtest\python-opencv05\black.jpg'。