How to solve the error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

Encountering "(-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'" error usually indicates that the input image is empty ​cvtColor()​when To resolve this issue, try the following:

1. Check the image path: Make sure your image path is correct and the image file exists. If the image file does not exist or the path is wrong, it will lead to failure to read the image, which will lead to ​cvtColor()​an error .
2. Check image reading: ​cvtColor()​Before ​​, make sure the image is read successfully. An image can be read using ​cv2.imread()​the function and check if the return value is empty. If the image read fails, it may be because the image format is not supported or the image file is corrupted.
3. Check image dimensions: Before color conversion, check that the dimensions of the image meet the requirements. Some color conversion functions have restrictions on the size of the image. If the image size does not meet the requirements, the conversion will fail.
4. Check the number of image channels: Some color conversion functions require the input image to have a specific number of channels, such as only one channel for grayscale images and three channels for color images. Before doing color conversion, you can use ​image.shape​the attribute to check the number of channels of the image and make sure it meets the requirements.
5. Check the image data type: The color conversion function also has requirements for the data type of the image, usually an unsigned 8-bit integer ( ​uint8​​​​) type. The data type of an image can be checked using ​image.dtype​the attribute and ensure compliance.

Here is a simple sample code that demonstrates how to use ​cvtColor()​the function to convert a color image to a grayscale image:

pythonCopy codeimport cv2
try:
    # 读取彩色图像
    image = cv2.imread('image.jpg')
    
    # 检查图像是否为空
    if image is None:
        print("Error: Failed to read image")
        exit()
    
    # 将彩色图像转换为灰度图像
    gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    
    # 显示原始图像和灰度图像
    cv2.imshow('Original Image', image)
    cv2.imshow('Gray Image', gray_image)
    cv2.waitKey(0)
    cv2.destroyAllWindows()
    
except Exception as e:
    print("Error:", e)

Please make sure you have installed OpenCV correctly and ​image.jpg​replace with your own path to the color image. In this sample code, first use ​cv2.imread()​the function to read the color image, then use ​cv2.cvtColor()​the function to convert the color image to a grayscale image, and display the result. If you encounter the "(-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'" error, please troubleshoot and solve it according to the methods mentioned above.