Converts an image to grayscale using the crude average of the r, g, and b

def convert_to_grayscale(image):
  gray_image = image.copy()
  gray_image[:, :, 0] = .2126 * image[:, :, 0]
  gray_image[:, :, 1] = .7152 * image[:, :, 1]
  gray_image[:, :, 2] = .0722 * image[:, :, 2]
  return gray_image