In Opencv, imag=cv2.cvtColor(imag,cv2.COLOR_BGR2GRAY) error: error:!_src.empty() in function 'cv::cvtColor'

Opencv,imag=cv2.cvtColor(imag,cv2.COLOR_BGR2GRAY) 报错：error:!_src.empty() in function ‘cv::cvtColor’

熟练使用Ctrl+C和Ctrl+V大法后

import cv2
path=r"296059.png"
imag=cv2.imdecode(np.fromfile(path),-1)
imag=cv2.cvtColor(imag,cv2.COLOR_BGR2GRAY) 

运行报错：cv2.error: OpenCV(4.6.0) D:\a\opencv-python\opencv-python\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function ‘cv::cvtColor’

此处：原因有很多种,可能有以下几个原因：

1.图片路径错误,Maybe the image path does not exist
2.To write image suffix
3.There is a Chinese path in the picture

If the above reasons are excluded,可以尝试以下方法：
解决方法1：
Images are divided into single-channel and multi-channel
单通道图像,直接cv2.imread(path, 0)Read in single channel mode.

import cv2
path=r"296059.png"
imag=cv2.imdecode(np.fromfile(path),-1)
imag=cv2.imread(path,0) 

解决方法2：
解决方案来源于(-215:Assertion failed) !_src.empty() in function ‘cv::cvtColor‘

#读取图片
import cv2
imag = cv2.imdecode(np.fromfile(img_path, dtype=np.uint8), 1)

imag = cv2.imdecode(np.fromfile(img_path, dtype=np.uint8), -1)  # 读入完整图片,见下面解释

imag = cv2.imdecode(np.fromfile(img_path, dtype=np.uint8), 0)  # 读成灰度
 
imag = cv2.imdecode(np.fromfile(img_path, dtype=np.uint8), 1)  # 读成彩图

在cv2.imdecode中补充：dtype=np.uint8,
如下解决：

import cv2
path=r"296059.png"
imag=cv2.imdecode(np.fromfile(path,dtype=np.uint8),1)
imag=cv2.cvtColor(imag,cv2.COLOR_BGR2GRAY)