OpenCV Error: '(-215:Assertion failed) !_src.empty()' in cvtColor Function - Solution and Explanation

This error message indicates an assertion failure in the 'cvtColor' function of the OpenCV library. It asserts that the input image ('_src') is not empty.

This error usually occurs when the input image you are trying to process is empty or null. To resolve it, ensure that the input image is valid before calling the 'cvtColor' function.

Here's an example demonstrating how to check if an image is empty before processing it with OpenCV:

import cv2

# Load image
img = cv2.imread('image.jpg')

# Check if image is empty
if img is None:
    print("Error: Could not read image")
else:
    # Process image
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

In this example, we load an image using the 'imread' function. We then check if the image is empty using the 'is None' condition. If the image is not empty, we proceed to process it using the 'cvtColor' function.