code: def rgb_to_y(image: Tensor) -> Tensor:
      r"""Convert an RGB image to Y.
  
      Args:
          image: RGB Image to be converted to Y with shape :math:`(*, 3, H, W)`.
  
      Returns:
          Y version of the image with shape :math:`(*, 1, H, W)`.
  
      Examples:
          >>> input = torch.rand(2, 3, 4, 5)
          >>> output = rgb_to_y(input)  # 2x1x4x5
      """
      if not isinstance(image, Tensor):
          raise TypeError(
              f"Input type is not a Tensor. Got {type(image)}"
          )
  
      if len(image.shape) < 3 or image.shape[-3] != 3:
          raise ValueError(
              f"Input size must have a shape of (*, 3, H, W). Got {image.shape}"
          )
  
      r: Tensor = image[..., 0:1, :, :]
      g: Tensor = image[..., 1:2, :, :]
      b: Tensor = image[..., 2:3, :, :]
  
      y: Tensor = _rgb_to_y(r, g, b)
      return y
  
file_path: kornia/kornia/color/ycbcr.py
imports: import torch
  from torch import Tensor, nn
label_desc: Use image node_id 3 for calling a global function with example usage: rgb_to_y(image) and returns: y