如何在pygame中制作Surface的灰度副本？

import pygame

pygame.init()

image = pygame.image.load("your_image.png")

gray_image = pygame.Surface(image.get_size(), flags=pygame.SRCALPHA)

average_color = pygame.transform.average_color(image)

gray_image = pygame.transform.average_surface(image, average_color, (255, 255, 255), (0, 0, 0))

screen = pygame.display.set_mode((800, 600))
screen.blit(gray_image, (0, 0))
pygame.display.update()