Convert RGB Image to Grayscale

Task: RGB to Grayscale Conversion

In this task, you will implement a function rgb_to_grayscale(image) that converts an RGB image to a grayscale image using the luminosity method.

The input image is represented as a 3D array of shape (H, W, 3), where H is height, W is width, and 3 represents the RGB color channels. Each pixel value should be in the range [0, 255].

Your Task:

Implement the function rgb_to_grayscale(image) to:

1. Convert the RGB image to grayscale using the standard luminosity coefficients for human perception of color brightness.
2. Return the grayscale image as a 2D list with pixel values rounded to integers.
3. Handle edge cases:
   • If the input is not a valid 3D array with 3 color channels.
   • If the image has empty dimensions.
   • If any pixel values are outside the valid range (0-255).

For any of these edge cases, the function should return -1.

import numpy as np

def rgb_to_grayscale(image):
    """
    Convert an RGB image to grayscale using luminosity method.
    
    Args:
        image: RGB image as list or numpy array of shape (H, W, 3)
               with values in range [0, 255]
    
    Returns:
        Grayscale image as 2D list with integer values,
        or -1 if input is invalid
    """
    # Write your code here
    pass